CHANGELOG

v3.1.21 (2017-05-22)
--------------------

* fixed issue #2488:  AQL operator IN error when data use base64 chars

* more randomness in seeding RNG

v3.1.20 (2017-05-16)
--------------------

* fixed incorrect sorting for distributeShardsLike

* improve reliability of AgencyComm communication with Agency

* fixed shard numbering bug, where ids were erouneously incremented by 1

* remove an unnecessary precondition in createCollectionCoordinator

* funny fail rotation fix

* fix in SimpleHttpClient for correct advancement of readBufferOffset

* forward SIG_HUP in supervisor process to the server process to fix logrotaion
  You need to stop the remaining arangod server process manually for the upgrade to work.

v3.1.19 (2017-04-28)
--------------------

* fixed issue #2453: GraphBrowser "Expand" function doesn't load all possible edges

* fixed issue #2448: Intermittent issue where ArangoDB Web UI takes no action when Delete button is clicked for a document

* fixed issue #2442: Frontend shows already deleted databases during login

* added 'x-content-type-options: nosniff' to avoid MSIE bug

* fixed issue #2441: dead/old link in foxx-manager help

* fixed issue #2440: Indexing break replication

* Fixed a StackOverflow issue in Traversal and ShortestPath. Occured if many (>1000) input
  values in a row do not return any result. Fixes issue: #2445

* fix occasional hanging shutdowns on OS X

* reduce the maximal wait time in exponential backoff when waiting for locks.
  This improves fairness of the collection locks under high load.

v3.1.18 (2017-04-18)
--------------------

* fixed error in continuous synchronization of collections

* fixed spurious hangs on server shutdown

* better error messages during restore collection

* completely overhaul supervision. More detailed tests

* fixed a dead-lock situation in cluster traversers, it could happen in
  rare cases if the computation on one DBServer could be completed much earlier
  than the other server. It could also be restricted to SmartGraphs only.

* (Enterprise only) fixed a bug in SmartGraph DepthFirstSearch. In some
  more complicated queries, the maxDepth limit of 1 was not considered strictly
  enough, causing the traverser to do unlimited depth searches.

* fixed issue #2415

* fixed issue #2422

* fixed issue #1974


v3.1.17 (2017-04-04)
--------------------

* (Enterprise only) fixed a bug where replicationFactor was not correctly
  forwarded in SmartGraph creation

* fixed issue #2404

* fixed issue #2403

  this restores the default read-cache size value for RAM sizes of less than 
  4 GB to the default size the read cache had in 3.1.15 and before. 3.1.16
  decreased the default value too much for small RAM sizes.

* fixed issue #2397

* ui - fixed smart graph option not appearing

* fixed issue #2389

* fixed issue #2400


v3.1.16 (2017-03-27)
--------------------

* fixed issue #2392

* try to raise file descriptors to at least 8192, warn otherwise

* ui - aql editor improvements + updated ace editor version (memory leak)

* fixed lost HTTP requests

* ui - fixed some event issues

* avoid name resolution when given connection string is a valid ip address

* helps with issue #1842, bug in COLLECT statement in connection with LIMIT.

* fix locking bug in cluster traversals

* increase lock timeout defaults

* increase various cluster timeouts

* limit default target size for revision cache to 1GB, which is better for
  tight RAM situations (used to be 40% of (totalRAM - 1GB), use
  --database.revision-cache-target-size <VALUEINBYTES> to get back the
  old behaviour

* fixed a bug with restarted servers indicating status as "STARTUP"
  rather that "SERVING" in Nodes UI.

v3.1.15 (2017-03-20)
--------------------

* add logrotate configuration as requested in #2355

* fixed issue #2376

* ui - changed document api due a chrome bug

* ui - fixed a submenu bug

* added endpoint /_api/cluster/endpoints in cluster case to get all
  coordinator endpoints

* fix documentation of /_api/endpoint, declaring this API obsolete.

* Foxx response objects now have a `type` method for manipulating the content-type header

* Foxx tests now support `xunit` and `tap` reporters


v3.1.14 (2017-03-13)
--------------------

* ui - added feature request (multiple start nodes within graph viewer) #2317

* added missing locks to authentication cache methods

* ui - fixed wrong merge of statistics information from different coordinators

* ui - fixed issue #2316

* ui - fixed wrong protocol usage within encrypted environment

* fixed compile error on Mac Yosemite

* minor UI fixes

* FailedServer job with breaking bug

v3.1.13 (2017-03-06)
--------------------

* fixed issue #2350

* fixed issue #2349

* fixed issue #2346

* fixed variables parsing in GraphQL

* fixed issue #2214

* fixed issue #2342

* changed thread handling to queue only user requests on coordinator

* use exponential backoff when waiting for collection locks

* repair short name server lookup in cluster in the case of a removed
  server


v3.1.12 (2017-02-28)
--------------------

* disable shell color escape sequences on Windows

* fixed issue #2326

* fixed issue #2320

* fixed issue #2315

* fixed a race condition when closing a connection

* raised default hard limit on threads for very small to 64

* fixed negative counting of http connection in UI

* fixed a race when renaming collections

* fixed a race when dropping databases

* fixed a rare race in agency compaction


v3.1.11 (2017-02-17)
--------------------

* fixed a race between connection closing and sending out last chunks of data to clients
  when the "Connection: close" HTTP header was set in requests

* ui: optimized smart graph creation usability

* ui: fixed #2308

* fixed a race in async task cancellation via `require("@arangodb/tasks").unregisterTask()`

* fixed spuriously hanging threads in cluster AQL that could sit idle for a few minutes

* fixed potential numeric overflow for big index ids in index deletion API

* fixed sort issue in cluster, occurring when one of the local sort buffers of a
  GatherNode was empty

* reduce number of HTTP requests made for certain kinds of join queries in cluster,
  leading to speedup of some join queries

* supervision deals with demised coordinators correctly again

* implement a timeout in TraverserEngineRegistry

* agent communication reduced in large batches of append entries RPCs

* inception no longer estimates RAFT timings

* compaction in agents has been moved to a separate thread

* replicated logs hold local timestamps

* supervision jobs failed leader and failed follower revisited for
  function in precarious stability situations

* fixed bug in random number generator for 64bit int


v3.1.10 (2017-02-02)
--------------------

* updated versions of bundled node modules:
  - joi: from 8.4.2 to 9.2.0
  - joi-to-json-schema: from 2.2.0 to 2.3.0
  - sinon: from 1.17.4 to 1.17.6
  - lodash: from 4.13.1 to 4.16.6

* added shortcut for AQL ternary operator
  instead of `condition ? true-part : false-part` it is now possible to also use a
  shortcut variant `condition ? : false-part`, e.g.

      FOR doc IN docs RETURN doc.value ?: 'not present'

  instead of

      FOR doc IN docs RETURN doc.value ? doc.value : 'not present'

* fixed wrong sorting order in cluster, if an index was used to sort with many
shards.

* added --replication-factor, --number-of-shards and --wait-for-sync to arangobench

* turn on UTF-8 string validation for VelocyPack values received via VST connections

* fixed issue #2257

* added optional detail flag for db.<collection>.count()
  setting the flag to `true` will make the count operation returned the per-shard
  counts for the collection:

      db._create("test", { numberOfShards: 10 });
      for (i = 0; i < 1000; ++i) {
	db.test.insert({value: i});
      }
      db.test.count(true);

      {
	"s100058" : 99,
	"s100057" : 103,
	"s100056" : 100,
	"s100050" : 94,
	"s100055" : 90,
	"s100054" : 122,
	"s100051" : 109,
	"s100059" : 99,
	"s100053" : 95,
	"s100052" : 89
      }

* added optional memory limit for AQL queries:

      db._query("FOR i IN 1..100000 SORT i RETURN i", {}, { options: { memoryLimit: 100000 } });

  This option limits the default maximum amount of memory (in bytes) that a single 
  AQL query can use.
  When a single AQL query reaches the specified limit value, the query will be
  aborted with a *resource limit exceeded* exception. In a cluster, the memory
  accounting is done per shard, so the limit value is effectively a memory limit per
  query per shard.

  The global limit value can be overriden per query by setting the *memoryLimit* 
  option value for individual queries when running an AQL query. 

* added server startup option `--query.memory-limit`

* added convenience function to create vertex-centric indexes.

  Usage: `db.collection.ensureVertexCentricIndex("label", {type: "hash", direction: "outbound"})`
  That will create an index that can be used on OUTBOUND with filtering on the
  edge attribute `label`.

* added option -D to define a configuration file environment key=value

* changed encoding behavior for URLs encoded in the C++ code of ArangoDB:
  previously the special characters `-`, `_`, `~` and `.` were returned as-is 
  after URL-encoding, now `.` will be encoded to be `%2e`. 
  This also changes the behavior of how incoming URIs are processed: previously
  occurrences of `..` in incoming request URIs were collapsed (e.g. `a/../b/` was 
  collapsed to a plain `b/`). Now `..` in incoming request URIs are not collapsed.

* improve cluster stability in various ways

* add support for Swagger tags in Foxx


v3.1.9 (2017-01-23)
-------------------

* MacOS CLI package: store databases and apps in the users home directory

* ui: fixed re-login issue within a non system db, when tab was closed

* fixed a race in the VelocyStream Commtask implementation

* fixed issue #2256


v3.1.8 (2017-01-09)
-------------------

* add Windows silent installer

* add handling of debug symbols during Linux & windows release builds.

* fixed issue #2181

* fixed issue #2248: reduce V8 max old space size from 3 GB to 1 GB on 32 bit systems

* upgraded Boost version to 1.62.0

* fixed issue #2238

* fixed issue #2234

* agents announce new endpoints in inception phase to leader

* agency leadership accepts updatet endpoints to given uuid

* unified endpoints replace localhost with 127.0.0.1

* fix several problems within an authenticated cluster


v3.1.7 (2016-12-29)
-------------------

* fixed one too many elections in RAFT

* new agency comm backported from devel


v3.1.6 (2016-12-20)
-------------------

* fixed issue #2227

* fixed issue #2220

* agency constituent/agent bug fixes in race conditions picking up
  leadership

* supervision does not need waking up anymore as it is running
  regardless

* agents challenge their leadership more rigorously


v3.1.5 (2016-12-16)
-------------------

* lowered default value of `--database.revision-cache-target-size` from 75% of
  RAM to less than 40% of RAM

* fixed issue #2218

* fixed issue #2217

* Foxx router.get/post/etc handler argument can no longer accidentally omitted

* fixed issue #2223


v3.1.4 (2016-12-08)
-------------------

* fixed issue #2211

* fixed issue #2204

* at cluster start, coordinators wait until at least one DBserver is there,
  and either at least two DBservers are there or 15s have passed, before they
  initiate the bootstrap of system collections.

* more robust agency startup from devel

* supervision's AddFollower adds many followers at once

* supervision has new FailedFollower job

* agency's Node has new method getArray

* agency RAFT timing estimates more conservative in waitForSync
  scenario
  
* agency RAFT timing estimates capped at maximum 2.0/10.0 for low/high


v3.1.3 (2016-12-02)
-------------------

* fix a traversal bug when using skiplist indexes:
  if we have a skiplist of ["a", "unused", "_from"] and a traversal like:
  FOR v,e,p IN OUTBOUND @start @@edges
    FILTER p.edges[0].a == 'foo'
    RETURN v
  And the above index applied on "a" is considered better than EdgeIndex, than
  the executor got into undefined behaviour.

* fix endless loop when trying to create a collection with replicationFactor: -1


v3.1.2 (2016-11-24)
-------------------

* added support for descriptions field in Foxx dependencies

* (Enterprise only) fixed a bug in the statistic report for SmartGraph traversals.
Now they state correctly how many documents were fetched from the index and how many
have been filtered.

* Prevent uniform shard distribution when replicationFactor == numServers

v3.1.1 (2016-11-15)
-------------------

* fixed issue #2176

* fixed issue #2168

* display index usage of traversals in AQL explainer output (previously missing)

* fixed isuse #2163

* preserve last-used HLC value across server starts

* allow more control over handling of pre-3.1 _rev values

  this changes the server startup option `--database.check-30-revisions` from a boolean (true/false)
  parameter to a string parameter with the following possible values:

  - "fail":
    will validate _rev values of 3.0 collections on collection loading and throw an exception when invalid _rev values are found.
    in this case collections with invalid _rev values are marked as corrupted and cannot be used in the ArangoDB 3.1 instance.
    the fix procedure for such collections is to export the collections from 3.0 database with arangodump and restore them in 3.1 with arangorestore.
    collections that do not contain invalid _rev values are marked as ok and will not be re-checked on following loads.
    collections that contain invalid _rev values will be re-checked on following loads.

  - "true":
    will validate _rev values of 3.0 collections on collection loading and print a warning when invalid _rev values are found.
    in this case collections with invalid _rev values can be used in the ArangoDB 3.1 instance.
    however, subsequent operations on documents with invalid _rev values may silently fail or fail with explicit errors.
    the fix procedure for such collections is to export the collections from 3.0 database with arangodump and restore them in 3.1 with arangorestore.
    collections that do not contain invalid _rev values are marked as ok and will not be re-checked on following loads.
    collections that contain invalid _rev values will be re-checked on following loads.

  - "false":
    will not validate _rev values on collection loading and not print warnings.
    no hint is given when invalid _rev values are found.
    subsequent operations on documents with invalid _rev values may silently fail or fail with explicit errors.
    this setting does not affect whether collections are re-checked later.
    collections will be re-checked on following loads if `--database.check-30-revisions` is later set to either `true` or `fail`.

  The change also suppresses warnings that were printed when collections were restored using arangorestore, and the restore
  data contained invalid _rev values. Now these warnings are suppressed, and new HLC _rev values are generated for these documents
  as before.

* added missing functions to AQL syntax highlighter in web interface

* fixed display of `ANY` direction in traversal explainer output (direction `ANY` was shown as either
  `INBOUND` or `OUTBOUND`)

* changed behavior of toJSON() function when serializing an object before saving it in the database

  if an object provides a toJSON() function, this function is still called for serializing it.
  the change is that the result of toJSON() is not stringified anymore, but saved as is. previous
  versions of ArangoDB called toJSON() and after that additionally stringified its result.

  This change will affect the saving of JS Buffer objects, which will now be saved as arrays of
  bytes instead of a comma-separated string of the Buffer's byte contents.

* allow creating unique indexes on more attributes than present in shardKeys

  The following combinations of shardKeys and indexKeys are allowed/not allowed:

  shardKeys     indexKeys
      a             a        ok
      a             b    not ok
      a           a b        ok
    a b             a    not ok
    a b             b    not ok
    a b           a b        ok
    a b         a b c        ok
  a b c           a b    not ok
  a b c         a b c        ok

* fixed wrong version in web interface login screen (EE only)

* make web interface not display an exclamation mark next to ArangoDB version number 3.1

* fixed search for arbitrary document attributes in web interface in case multiple
  search values were used on different attribute names. in this case, the search always
  produced an empty result

* disallow updating `_from` and `_to` values of edges in Smart Graphs. Updating these
  attributes would lead to potential redistribution of edges to other shards, which must be 
  avoided.

* fixed issue #2148

* updated graphql-sync dependency to 0.6.2

* fixed issue #2156

* fixed CRC4 assembly linkage


v3.1.0 (2016-10-29)
-------------------

* added AQL function `DISTANCE` to calculate the distance between two arbitrary
  coordinates (haversine formula)

* fixed issue #2110

* added Auto-aptation of RAFT timings as calculations only


v3.1.rc2 (2016-10-10)
---------------------

* second release candidate


v3.1.rc1 (2016-09-30)
---------------------

* first release candidate


v3.1.alpha2 (2016-09-01)
------------------------

* added module.context.createDocumentationRouter to replace module.context.apiDocumentation

* bug in RAFT implementation of reads. dethroned leader still answered requests in isolation

* ui: added new graph viewer

* ui: aql-editor added tabular & graph display

* ui: aql-editor improved usability

* ui: aql-editor: query profiling support

* fixed issue #2109

* fixed issue #2111

* fixed issue #2075

* added AQL function `DISTANCE` to calculate the distance between two arbitrary
  coordinates (haversine formula)

* rewrote scheduler and dispatcher based on boost::asio

  parameters changed:
    `--scheduler.threads` and `--server.threads` are now merged into a single one: `--server.threads`

    hidden `--server.extra-threads` has been removed

    hidden `--server.aql-threads` has been removed

    hidden `--server.backend` has been removed

    hidden `--server.show-backends` has been removed

    hidden `--server.thread-affinity` has been removed

* fixed issue #2086

* fixed issue #2079

* fixed issue #2071

  make the AQL query optimizer inject filter condition expressions referred to
  by variables during filter condition aggregation.
  For example, in the following query

      FOR doc IN collection
        LET cond1 = (doc.value == 1)
        LET cond2 = (doc.value == 2)
        FILTER cond1 || cond2
        RETURN { doc, cond1, cond2 }

  the optimizer will now inject the conditions for `cond1` and `cond2` into the filter
  condition `cond1 || cond2`, expanding it to `(doc.value == 1) || (doc.value == 2)`
  and making these conditions available for index searching.

  Note that the optimizer previously already injected some conditions into other
  conditions, but only if the variable that defined the condition was not used
  elsewhere. For example, the filter condition in the query

      FOR doc IN collection
        LET cond = (doc.value == 1)
        FILTER cond
        RETURN { doc }

  already got optimized before because `cond` was only used once in the query and
  the optimizer decided to inject it into the place where it was used.

  This only worked for variables that were referred to once in the query.
  When a variable was used multiple times, the condition was not injected as
  in the following query:

      FOR doc IN collection
        LET cond = (doc.value == 1)
        FILTER cond
        RETURN { doc, cond }

  The fix for #2070 now will enable this optimization so that the query can
  use an index on `doc.value` if available.

* changed behavior of AQL array comparison operators for empty arrays:
  * `ALL` and `ANY` now always return `false` when the left-hand operand is an
    empty array. The behavior for non-empty arrays does not change:
    * `[] ALL == 1` will return `false`
    * `[1] ALL == 1` will return `true`
    * `[1, 2] ALL == 1` will return `false`
    * `[2, 2] ALL == 1` will return `false`
    * `[] ANY == 1` will return `false`
    * `[1] ANY == 1` will return `true`
    * `[1, 2] ANY == 1` will return `true`
    * `[2, 2] ANY == 1` will return `false`
  * `NONE` now always returns `true` when the left-hand operand is an empty array.
    The behavior for non-empty arrays does not change:
    * `[] NONE == 1` will return `true`
    * `[1] NONE == 1` will return `false`
    * `[1, 2] NONE == 1` will return `false`
    * `[2, 2] NONE == 1` will return `true`

* added experimental AQL functions `JSON_STRINGIFY` and `JSON_PARSE`

* added experimental support for incoming gzip-compressed requests

* added HTTP REST APIs for online loglevel adjustments:

  - GET `/_admin/log/level` returns the current loglevel settings
  - PUT `/_admin/log/level` modifies the current loglevel settings

* PATCH /_api/gharial/{graph-name}/vertex/{collection-name}/{vertex-key}
  - changed default value for keepNull to true

* PATCH /_api/gharial/{graph-name}/edge/{collection-name}/{edge-key}
  - changed default value for keepNull to true

* renamed `maximalSize` attribute in parameter.json files to `journalSize`

  The `maximalSize` attribute will still be picked up from collections that
  have not been adjusted. Responses from the replication API will now also use
  `journalSize` instead of `maximalSize`.

* added `--cluster.system-replication-factor` in order to adjust the
  replication factor for new system collections

* fixed issue #2012

* added a memory expection in case V8 memory gets too low

* added Optimizer Rule for other indexes in Traversals
  this allows AQL traversals to use other indexes than the edge index.
  So traversals with filters on edges can now make use of more specific
  indexes, e.g.

      FOR v, e, p IN 2 OUTBOUND @start @@edge FILTER p.edges[0].foo == "bar"

  will prefer a Hash Index on [_from, foo] above the EdgeIndex.

* fixed epoch computation in hybrid logical clock

* fixed thread affinity

* replaced require("internal").db by require("@arangodb").db

* added option `--skip-lines` for arangoimp
  this allows skipping the first few lines from the import file in case the
  CSV or TSV import are used

* fixed periodic jobs: there should be only one instance running - even if it
  runs longer than the period

* improved performance of primary index and edge index lookups

* optimizations for AQL `[*]` operator in case no filter, no projection and
  no offset/limit are used

* added AQL function `OUTERSECTION` to return the symmetric difference of its
  input arguments

* Foxx manifests of installed services are now saved to disk with indentation

* Foxx tests and scripts in development mode should now always respect updated
  files instead of loading stale modules

* When disabling Foxx development mode the setup script is now re-run

* Foxx now provides an easy way to directly serve GraphQL requests using the
  `@arangodb/foxx/graphql` module and the bundled `graphql-sync` dependency

* Foxx OAuth2 module now correctly passes the `access_token` to the OAuth2 server

* added iconv-lite and timezone modules

* web interface now allows installing GitHub and zip services in legacy mode

* added module.context.createDocumentationRouter to replace module.context.apiDocumentation

* bug in RAFT implementation of reads. dethroned leader still answered
  requests in isolation

* all lambdas in ClusterInfo might have been left with dangling references.

* Agency bug fix for handling of empty json objects as values.

* Foxx tests no longer support the Mocha QUnit interface as this resulted in weird
  inconsistencies in the BDD and TDD interfaces. This fixes the TDD interface
  as well as out-of-sequence problems when using the BDD before/after functions.

* updated bundled JavaScript modules to latest versions; joi has been updated from 8.4 to 9.2
  (see [joi 9.0.0 release notes](https://github.com/hapijs/joi/issues/920) for information on
  breaking changes and new features)

* fixed issue #2139

* updated graphql-sync dependency to 0.6.2

* fixed issue #2156


v3.0.13 (XXXX-XX-XX)
--------------------

* fixed issue #2315

* fixed issue #2210


v3.0.12 (2016-11-23)
--------------------

* fixed issue #2176

* fixed issue #2168

* fixed issues #2149, #2159

* fixed error reporting for issue #2158

* fixed assembly linkage bug in CRC4 module

* added support for descriptions field in Foxx dependencies


v3.0.11 (2016-11-08)
--------------------

* fixed issue #2140: supervisor dies instead of respawning child

* fixed issue #2131: use shard key value entered by user in web interface

* fixed issue #2129: cannot kill a long-run query

* fixed issue #2110

* fixed issue #2081

* fixed issue #2038

* changes to Foxx service configuration or dependencies should now be
  stored correctly when options are cleared or omitted

* Foxx tests no longer support the Mocha QUnit interface as this resulted in weird
  inconsistencies in the BDD and TDD interfaces. This fixes the TDD interface
  as well as out-of-sequence problems when using the BDD before/after functions.

* fixed issue #2148


v3.0.10 (2016-09-26)
--------------------

* fixed issue #2072

* fixed issue #2070

* fixed slow cluster starup issues. supervision will demonstrate more
  patience with db servers


v3.0.9 (2016-09-21)
-------------------

* fixed issue #2064

* fixed issue #2060

* speed up `collection.any()` and skiplist index creation

* fixed multiple issues where ClusterInfo bug hung agency in limbo
  timeouting on multiple collection and database callbacks


v3.0.8 (2016-09-14)
-------------------

* fixed issue #2052

* fixed issue #2005

* fixed issue #2039

* fixed multiple issues where ClusterInfo bug hung agency in limbo
  timeouting on multiple collection and database callbacks


v3.0.7 (2016-09-05)
-------------------

* new supervision job handles db server failure during collection creation.


v3.0.6 (2016-09-02)
-------------------

* fixed issue #2026

* slightly better error diagnostics for AQL query compilation and replication

* fixed issue #2018

* fixed issue #2015

* fixed issue #2012

* fixed wrong default value for arangoimp's `--on-duplicate` value

* fix execution of AQL traversal expressions when there are multiple
  conditions that refer to variables set outside the traversal

* properly return HTTP 503 in JS actions when backend is gone

* supervision creates new key in agency for failed servers

* new shards will not be allocated on failed or cleaned servers


v3.0.5 (2016-08-18)
-------------------

* execute AQL ternary operator via C++ if possible

* fixed issue #1977

* fixed extraction of _id attribute in AQL traversal conditions

* fix SSL agency endpoint

* Minimum RAFT timeout was one order of magnitude to short.

* Optimized RAFT RPCs from leader to followers for efficiency.

* Optimized RAFT RPC handling on followers with respect to compaction.

* Fixed bug in handling of duplicates and overlapping logs

* Fixed bug in supervision take over after leadership change.

v3.0.4 (2016-08-01)
-------------------

* added missing lock for periodic jobs access

* fix multiple foxx related cluster issues

* fix handling of empty AQL query strings

* fixed issue in `INTERSECTION` AQL function with duplicate elements
  in the source arrays

* fixed issue #1970

* fixed issue #1968

* fixed issue #1967

* fixed issue #1962

* fixed issue #1959

* replaced require("internal").db by require("@arangodb").db

* fixed issue #1954

* fixed issue #1953

* fixed issue #1950

* fixed issue #1949

* fixed issue #1943

* fixed segfault in V8, by backporting https://bugs.chromium.org/p/v8/issues/detail?id=5033

* Foxx OAuth2 module now correctly passes the `access_token` to the OAuth2 server

* fixed credentialed CORS requests properly respecting --http.trusted-origin

* fixed a crash in V8Periodic task (forgotten lock)

* fixed two bugs in synchronous replication (syncCollectionFinalize)


v3.0.3 (2016-07-17)
-------------------

* fixed issue #1942

* fixed issue #1941

* fixed array index batch insertion issues for hash indexes that caused problems when
  no elements remained for insertion

* fixed AQL MERGE() function with External objects originating from traversals

* fixed some logfile recovery errors with error message "document not found"

* fixed issue #1937

* fixed issue #1936

* improved performance of arangorestore in clusters with synchronous
  replication

* Foxx tests and scripts in development mode should now always respect updated
  files instead of loading stale modules

* When disabling Foxx development mode the setup script is now re-run

* Foxx manifests of installed services are now saved to disk with indentation


v3.0.2 (2016-07-09)
-------------------

* fixed assertion failure in case multiple remove operations were used in the same query

* fixed upsert behavior in case upsert was used in a loop with the same document example

* fixed issue #1930

* don't expose local file paths in Foxx error messages.

* fixed issue #1929

* make arangodump dump the attribute `isSystem` when dumping the structure
  of a collection, additionally make arangorestore not fail when the attribute
  is missing

* fixed "Could not extract custom attribute" issue when using COLLECT with
  MIN/MAX functions in some contexts

* honor presence of persistent index for sorting

* make AQL query optimizer not skip "use-indexes-rule", even if enough
  plans have been created already

* make AQL optimizer not skip "use-indexes-rule", even if enough execution plans
  have been created already

* fix double precision value loss in VelocyPack JSON parser

* added missing SSL support for arangorestore

* improved cluster import performance

* fix Foxx thumbnails on DC/OS

* fix Foxx configuration not being saved

* fix Foxx app access from within the frontend on DC/OS

* add option --default-replication-factor to arangorestore and simplify
  the control over the number of shards when restoring

* fix a bug in the VPack -> V8 conversion if special attributes _key,
  _id, _rev, _from and _to had non-string values, which is allowed
  below the top level

* fix malloc_usable_size for darwin


v3.0.1 (2016-06-30)
-------------------

* fixed periodic jobs: there should be only one instance running - even if it
  runs longer than the period

* increase max. number of collections in AQL queries from 32 to 256

* fixed issue #1916: header "authorization" is required" when opening
  services page

* fixed issue #1915: Explain: member out of range

* fixed issue #1914: fix unterminated buffer

* don't remove lockfile if we are the same (now stale) pid
  fixes docker setups (our pid will always be 1)

* do not use revision id comparisons in compaction for determining whether a
  revision is obsolete, but marker memory addresses
  this ensures revision ids don't matter when compacting documents

* escape Unicode characters in JSON HTTP responses
  this converts UTF-8 characters in HTTP responses of arangod into `\uXXXX`
  escape sequences. This makes the HTTP responses fit into the 7 bit ASCII
  character range, which speeds up HTTP response parsing for some clients,
  namely node.js/v8

* add write before read collections when starting a user transaction
  this allows specifying the same collection in both read and write mode without
  unintended side effects

* fixed buffer overrun that occurred when building very large result sets

* index lookup optimizations for primary index and edge index

* fixed "collection is a nullptr" issue when starting a traversal from a transaction

* enable /_api/import on coordinator servers


v3.0.0 (2016-06-22)
-------------------

* minor GUI fixxes

* fix for replication and nonces


v3.0.0-rc3 (2016-06-19)
-----------------------

* renamed various Foxx errors to no longer refer to Foxx services as apps

* adjusted various error messages in Foxx to be more informative

* specifying "files" in a Foxx manifest to be mounted at the service root
  no longer results in 404s when trying to access non-file routes

* undeclared path parameters in Foxx no longer break the service

* trusted reverse proxy support is now handled more consistently

* ArangoDB request compatibility and user are now exposed in Foxx

* all bundled NPM modules have been upgraded to their latest versions


v3.0.0-rc2 (2016-06-12)
-----------------------

* added option `--server.max-packet-size` for client tools

* renamed option `--server.ssl-protocol` to `--ssl.protocol` in client tools
  (was already done for arangod, but overlooked for client tools)

* fix handling of `--ssl.protocol` value 5 (TLS v1.2) in client tools, which
  claimed to support it but didn't

* config file can use '@include' to include a different config file as base


v3.0.0-rc1 (2016-06-10)
-----------------------

* the user management has changed: it now has users that are independent of
  databases. A user can have one or more database assigned to the user.

* forward ported V8 Comparator bugfix for inline heuristics from
  https://github.com/v8/v8/commit/5ff7901e24c2c6029114567de5a08ed0f1494c81

* changed to-string conversion for AQL objects and arrays, used by the AQL
  function `TO_STRING()` and implicit to-string casts in AQL

  - arrays are now converted into their JSON-stringify equivalents, e.g.

    - `[ ]` is now converted to `[]`
    - `[ 1, 2, 3 ]` is now converted to `[1,2,3]`
    - `[ "test", 1, 2 ] is now converted to `["test",1,2]`

    Previous versions of ArangoDB converted arrays with no members into the
    empty string, and non-empty arrays into a comma-separated list of member
    values, without the surrounding angular brackets. Additionally, string
    array members were not enclosed in quotes in the result string:

    - `[ ]` was converted to ``
    - `[ 1, 2, 3 ]` was converted to `1,2,3`
    - `[ "test", 1, 2 ] was converted to `test,1,2`

  - objects are now converted to their JSON-stringify equivalents, e.g.

    - `{ }` is converted to `{}`
    - `{ a: 1, b: 2 }` is converted to `{"a":1,"b":2}`
    - `{ "test" : "foobar" }` is converted to `{"test":"foobar"}`

    Previous versions of ArangoDB always converted objects into the string
    `[object Object]`

  This change affects also the AQL functions `CONCAT()` and `CONCAT_SEPARATOR()`
  which treated array values differently in previous versions. Previous versions
  of ArangoDB automatically flattened array values on the first level of the array,
  e.g. `CONCAT([1, 2, 3, [ 4, 5, 6 ]])` produced `1,2,3,4,5,6`. Now this will produce
  `[1,2,3,[4,5,6]]`. To flatten array members on the top level, you can now use
  the more explicit `CONCAT(FLATTEN([1, 2, 3, [4, 5, 6]], 1))`.

* added C++ implementations for AQL functions `SLICE()`, `CONTAINS()` and
  `RANDOM_TOKEN()`

* as a consequence of the upgrade to V8 version 5, the implementation of the
  JavaScript `Buffer` object had to be changed. JavaScript `Buffer` objects in
  ArangoDB now always store their data on the heap. There is no shared pool
  for small Buffer values, and no pointing into existing Buffer data when
  extracting slices. This change may increase the cost of creating Buffers with
  short contents or when peeking into existing Buffers, but was required for
  safer memory management and to prevent leaks.

* the `db` object's function `_listDatabases()` was renamed to just `_databases()`
  in order to make it more consistent with the existing `_collections()` function.
  Additionally the `db` object's `_listEndpoints()` function was renamed to just
  `_endpoints()`.

* changed default value of `--server.authentication` from `false` to `true` in
  configuration files etc/relative/arangod.conf and etc/arangodb/arangod.conf.in.
  This means the server will be started with authentication enabled by default,
  requiring all client connections to provide authentication data when connecting
  to ArangoDB. Authentication can still be turned off via setting the value of
  `--server.authentication` to `false` in ArangoDB's configuration files or by
  specifying the option on the command-line.

* Changed result format for querying all collections via the API GET `/_api/collection`.

  Previous versions of ArangoDB returned an object with an attribute named `collections`
  and an attribute named `names`. Both contained all available collections, but
  `collections` contained the collections as an array, and `names` contained the
  collections again, contained in an object in which the attribute names were the
  collection names, e.g.

  ```
  {
    "collections": [
      {"id":"5874437","name":"test","isSystem":false,"status":3,"type":2},
      {"id":"17343237","name":"something","isSystem":false,"status":3,"type":2},
      ...
    ],
    "names": {
      "test": {"id":"5874437","name":"test","isSystem":false,"status":3,"type":2},
      "something": {"id":"17343237","name":"something","isSystem":false,"status":3,"type":2},
      ...
    }
  }
  ```
  This result structure was redundant, and therefore has been simplified to just

  ```
  {
    "result": [
      {"id":"5874437","name":"test","isSystem":false,"status":3,"type":2},
      {"id":"17343237","name":"something","isSystem":false,"status":3,"type":2},
      ...
    ]
  }
  ```

  in ArangoDB 3.0.

* added AQL functions `TYPENAME()` and `HASH()`

* renamed arangob tool to arangobench

* added AQL string comparison operator `LIKE`

  The operator can be used to compare strings like this:

      value LIKE search

  The operator is currently implemented by calling the already existing AQL
  function `LIKE`.

  This change also makes `LIKE` an AQL keyword. Using `LIKE` in either case as
  an attribute or collection name in AQL thus requires quoting.

* make AQL optimizer rule "remove-unnecessary-calculations" fire in more cases

  The rule will now remove calculations that are used exactly once in other
  expressions (e.g. `LET a = doc RETURN a.value`) and calculations,
  or calculations that are just references (e.g. `LET a = b`).

* renamed AQL optimizer rule "merge-traversal-filter" to "optimize-traversals"
  Additionally, the optimizer rule will remove unused edge and path result variables
  from the traversal in case they are specified in the `FOR` section of the traversal,
  but not referenced later in the query. This saves constructing edges and paths
  results.

* added AQL optimizer rule "inline-subqueries"

  This rule can pull out certain subqueries that are used as an operand to a `FOR`
  loop one level higher, eliminating the subquery completely. For example, the query

      FOR i IN (FOR j IN [1,2,3] RETURN j) RETURN i

  will be transformed by the rule to:

      FOR i IN [1,2,3] RETURN i

  The query

      FOR name IN (FOR doc IN _users FILTER doc.status == 1 RETURN doc.name) LIMIT 2 RETURN name

  will be transformed into

      FOR tmp IN _users FILTER tmp.status == 1 LIMIT 2 RETURN tmp.name

  The rule will only fire when the subquery is used as an operand to a `FOR` loop, and
  if the subquery does not contain a `COLLECT` with an `INTO` variable.

* added new endpoint "srv://" for DNS service records

* The result order of the AQL functions VALUES and ATTRIBUTES has never been
  guaranteed and it only had the "correct" ordering by accident when iterating
  over objects that were not loaded from the database. This accidental behavior
  is now changed by introduction of VelocyPack. No ordering is guaranteed unless
  you specify the sort parameter.

* removed configure option `--enable-logger`

* added AQL array comparison operators

  All AQL comparison operators now also exist in an array variant. In the
  array variant, the operator is preceded with one of the keywords *ALL*, *ANY*
  or *NONE*. Using one of these keywords changes the operator behavior to
  execute the comparison operation for all, any, or none of its left hand
  argument values. It is therefore expected that the left hand argument
  of an array operator is an array.

  Examples:

      [ 1, 2, 3 ] ALL IN [ 2, 3, 4 ]   // false
      [ 1, 2, 3 ] ALL IN [ 1, 2, 3 ]   // true
      [ 1, 2, 3 ] NONE IN [ 3 ]        // false
      [ 1, 2, 3 ] NONE IN [ 23, 42 ]   // true
      [ 1, 2, 3 ] ANY IN [ 4, 5, 6 ]   // false
      [ 1, 2, 3 ] ANY IN [ 1, 42 ]     // true
      [ 1, 2, 3 ] ANY == 2             // true
      [ 1, 2, 3 ] ANY == 4             // false
      [ 1, 2, 3 ] ANY > 0              // true
      [ 1, 2, 3 ] ANY <= 1             // true
      [ 1, 2, 3 ] NONE < 99            // false
      [ 1, 2, 3 ] NONE > 10            // true
      [ 1, 2, 3 ] ALL > 2              // false
      [ 1, 2, 3 ] ALL > 0              // true
      [ 1, 2, 3 ] ALL >= 3             // false
      ["foo", "bar"] ALL != "moo"      // true
      ["foo", "bar"] NONE == "bar"     // false
      ["foo", "bar"] ANY == "foo"      // true

* improved AQL optimizer to remove unnecessary sort operations in more cases

* allow enclosing AQL identifiers in forward ticks in addition to using
  backward ticks

  This allows for convenient writing of AQL queries in JavaScript template strings
  (which are delimited with backticks themselves), e.g.

      var q = `FOR doc IN ´collection´ RETURN doc.´name´`;

* allow to set `print.limitString` to configure the number of characters
  to output before truncating

* make logging configurable per log "topic"

  `--log.level <level>` sets the global log level to <level>, e.g. `info`,
  `debug`, `trace`.

  `--log.level topic=<level>` sets the log level for a specific topic.
  Currently, the following topics exist: `collector`, `compactor`, `mmap`,
  `performance`, `queries`, and `requests`. `performance` and `requests` are
  set to FATAL by default. `queries` is set to info. All others are
  set to the global level by default.

  The new log option `--log.output <definition>` allows directing the global
  or per-topic log output to different outputs. The output definition
  "<definition>" can be one of

    "-" for stdin
    "+" for stderr
    "syslog://<syslog-facility>"
    "syslog://<syslog-facility>/<application-name>"
    "file://<relative-path>"

  The option can be specified multiple times in order to configure the output
  for different log topics. To set up a per-topic output configuration, use
  `--log.output <topic>=<definition>`, e.g.

    queries=file://queries.txt

  logs all queries to the file "queries.txt".

* the option `--log.requests-file` is now deprecated. Instead use

    `--log.level requests=info`
    `--log.output requests=file://requests.txt`

* the option `--log.facility` is now deprecated. Instead use

    `--log.output requests=syslog://facility`

* the option `--log.performance` is now deprecated. Instead use

    `--log.level performance=trace`

* removed option `--log.source-filter`

* removed configure option `--enable-logger`

* change collection directory names to include a random id component at the end

  The new pattern is `collection-<id>-<random>`, where `<id>` is the collection
  id and `<random>` is a random number. Previous versions of ArangoDB used a
  pattern `collection-<id>` without the random number.

  ArangoDB 3.0 understands both the old and name directory name patterns.

* removed mostly unused internal spin-lock implementation

* removed support for pre-Windows 7-style locks. This removes compatibility for
  Windows versions older than Windows 7 (e.g. Windows Vista, Windows XP) and
  Windows 2008R2 (e.g. Windows 2008).

* changed names of sub-threads started by arangod

* added option `--default-number-of-shards` to arangorestore, allowing creating
  collections with a specifiable number of shards from a non-cluster dump

* removed support for CoffeeScript source files

* removed undocumented SleepAndRequeue

* added WorkMonitor to inspect server threads

* when downloading a Foxx service from the web interface the suggested filename
  is now based on the service's mount path instead of simply "app.zip"

* the `@arangodb/request` response object now stores the parsed JSON response
  body in a property `json` instead of `body` when the request was made using the
  `json` option. The `body` instead contains the response body as a string.

* the Foxx API has changed significantly, 2.8 services are still supported
  using a backwards-compatible "legacy mode"


v2.8.12 (XXXX-XX-XX)
--------------------

* issue #2091: decrease connect timeout to 5 seconds on startup

* fixed issue #2072

* slightly better error diagnostics for some replication errors

* fixed issue #1977

* fixed issue in `INTERSECTION` AQL function with duplicate elements
  in the source arrays

* fixed issue #1962

* fixed issue #1959

* export aqlQuery template handler as require('org/arangodb').aql for forwards-compatibility


v2.8.11 (2016-07-13)
--------------------

* fixed array index batch insertion issues for hash indexes that caused problems when 
  no elements remained for insertion

* fixed issue #1937


v2.8.10 (2016-07-01)
--------------------

* make sure next local _rev value used for a document is at least as high as the
  _rev value supplied by external sources such as replication

* make adding a collection in both read- and write-mode to a transaction behave as
  expected (write includes read). This prevents the `unregister collection used in
  transaction` error

* fixed sometimes invalid result for `byExample(...).count()` when an index plus
  post-filtering was used

* fixed "collection is a nullptr" issue when starting a traversal from a transaction

* honor the value of startup option `--database.wait-for-sync` (that is used to control
  whether new collections are created with `waitForSync` set to `true` by default) also
  when creating collections via the HTTP API (and thus the ArangoShell). When creating
  a collection via these mechanisms, the option was ignored so far, which was inconsistent.

* fixed issue #1826: arangosh --javascript.execute: internal error (geo index issue)

* fixed issue #1823: Arango crashed hard executing very simple query on windows


v2.8.9 (2016-05-13)
-------------------

* fixed escaping and quoting of extra parameters for executables in Mac OS X App

* added "waiting for" status variable to web interface collection figures view

* fixed undefined behavior in query cache invaldation

* fixed access to /_admin/statistics API in case statistics are disable via option
  `--server.disable-statistics`

* Foxx manager will no longer fail hard when Foxx store is unreachable unless installing
  a service from the Foxx store (e.g. when behind a firewall or GitHub is unreachable).


v2.8.8 (2016-04-19)
-------------------

* fixed issue #1805: Query: internal error (location: arangod/Aql/AqlValue.cpp:182).
  Please report this error to arangodb.com (while executing)

* allow specifying collection name prefixes for `_from` and `_to` in arangoimp:

  To avoid specifying complete document ids (consisting of collection names and document
  keys) for *_from* and *_to* values when importing edges with arangoimp, there are now
  the options *--from-collection-prefix* and *--to-collection-prefix*.

  If specified, these values will be automatically prepended to each value in *_from*
  (or *_to* resp.). This allows specifying only document keys inside *_from* and/or *_to*.

  *Example*

      > arangoimp --from-collection-prefix users --to-collection-prefix products ...

  Importing the following document will then create an edge between *users/1234* and
  *products/4321*:

  ```js
  { "_from" : "1234", "_to" : "4321", "desc" : "users/1234 is connected to products/4321" }
  ```

* requests made with the interactive system API documentation in the web interface
  (Swagger) will now respect the active database instead of always using `_system`


v2.8.7 (2016-04-07)
-------------------

* optimized primary=>secondary failover

* fix to-boolean conversion for documents in AQL

* expose the User-Agent HTTP header from the ArangoShell since Github seems to
  require it now, and we use the ArangoShell for fetching Foxx repositories from Github

* work with http servers that only send

* fixed potential race condition between compactor and collector threads

* fix removal of temporary directories on arangosh exit

* javadoc-style comments in Foxx services are no longer interpreted as
  Foxx comments outside of controller/script/exports files (#1748)

* removed remaining references to class syntax for Foxx Model and Repository
  from the documentation

* added a safe-guard for corrupted master-pointer


v2.8.6 (2016-03-23)
-------------------

* arangosh can now execute JavaScript script files that contain a shebang
  in the first line of the file. This allows executing script files directly.

  Provided there is a script file `/path/to/script.js` with the shebang
  `#!arangosh --javascript.execute`:

      > cat /path/to/script.js
      #!arangosh --javascript.execute
      print("hello from script.js");

  If the script file is made executable

      > chmod a+x /path/to/script.js

  it can be invoked on the shell directly and use arangosh for its execution:

      > /path/to/script.js
      hello from script.js

  This did not work in previous versions of ArangoDB, as the whole script contents
  (including the shebang) were treated as JavaScript code.
  Now shebangs in script files will now be ignored for all files passed to arangosh's
  `--javascript.execute` parameter.

  The alternative way of executing a JavaScript file with arangosh still works:

      > arangosh --javascript.execute /path/to/script.js
      hello from script.js

* added missing reset of traversal state for nested traversals.
  The state of nested traversals (a traversal in an AQL query that was
  located in a repeatedly executed subquery or inside another FOR loop)
  was not reset properly, so that multiple invocations of the same nested
  traversal with different start vertices led to the nested traversal
  always using the start vertex provided on the first invocation.

* fixed issue #1781: ArangoDB startup time increased tremendously

* fixed issue #1783: SIGHUP should rotate the log


v2.8.5 (2016-03-11)
-------------------

* Add OpenSSL handler for TLS V1.2 as sugested by kurtkincaid in #1771

* fixed issue #1765 (The webinterface should display the correct query time)
  and #1770 (Display ACTUAL query time in aardvark's AQL editor)

* Windows: the unhandled exception handler now calls the windows logging
  facilities directly without locks.
  This fixes lockups on crashes from the logging framework.

* improve nullptr handling in logger.

* added new endpoint "srv://" for DNS service records

* `org/arangodb/request` no longer sets the content-type header to the
  string "undefined" when no content-type header should be sent (issue #1776)


v2.8.4 (2016-03-01)
-------------------

* global modules are no longer incorrectly resolved outside the ArangoDB
  JavaScript directory or the Foxx service's root directory (issue #1577)

* improved error messages from Foxx and JavaScript (issues #1564, #1565, #1744)


v2.8.3 (2016-02-22)
-------------------

* fixed AQL filter condition collapsing for deeply-nested cases, potentially
  enabling usage of indexes in some dedicated cases

* added parentheses in AQL explain command output to correctly display precedence
  of logical and arithmetic operators

* Foxx Model event listeners defined on the model are now correctly invoked by
  the Repository methods (issue #1665)

* Deleting a Foxx service in the frontend should now always succeed even if the
  files no longer exist on the file system (issue #1358)

* Routing actions loaded from the database no longer throw exceptions when
  trying to load other modules using "require"

* The `org/arangodb/request` response object now sets a property `json` to the
  parsed JSON response body in addition to overwriting the `body` property when
  the request was made using the `json` option.

* Improved Windows stability

* Fixed a bug in the interactive API documentation that would escape slashes
  in document-handle fields. Document handles are now provided as separate
  fields for collection name and document key.


v2.8.2 (2016-02-09)
-------------------

* the continuous replication applier will now prevent the master's WAL logfiles
  from being removed if they are still needed by the applier on the slave. This
  should help slaves that suffered from masters garbage collection WAL logfiles
  which would have been needed by the slave later.

  The initial synchronization will block removal of still needed WAL logfiles
  on the master for 10 minutes initially, and will extend this period when further
  requests are made to the master. Initial synchronization hands over its handle
  for blocking logfile removal to the continuous replication when started via
  the *setupReplication* function. In this case, continuous replication will
  extend the logfile removal blocking period for the required WAL logfiles when
  the slave makes additional requests.

  All handles that block logfile removal will time out automatically after at
  most 5 minutes should a master not be contacted by the slave anymore (e.g. in
  case the slave's replication is turned off, the slaves loses the connection
  to the master or the slave goes down).

* added all-in-one function *setupReplication* to synchronize data from master
  to slave and start the continuous replication:

      require("@arangodb/replication").setupReplication(configuration);

  The command will return when the initial synchronization is finished and the
  continuous replication has been started, or in case the initial synchronization
  has failed.

  If the initial synchronization is successful, the command will store the given
  configuration on the slave. It also configures the continuous replication to start
  automatically if the slave is restarted, i.e. *autoStart* is set to *true*.

  If the command is run while the slave's replication applier is already running,
  it will first stop the running applier, drop its configuration and do a
  resynchronization of data with the master. It will then use the provided configration,
  overwriting any previously existing replication configuration on the slave.

  The following example demonstrates how to use the command for setting up replication
  for the *_system* database. Note that it should be run on the slave and not the
  master:

      db._useDatabase("_system");
      require("@arangodb/replication").setupReplication({
        endpoint: "tcp://master.domain.org:8529",
        username: "myuser",
        password: "mypasswd",
        verbose: false,
        includeSystem: false,
        incremental: true,
        autoResync: true
      });

* the *sync* and *syncCollection* functions now always start the data synchronization
  as an asynchronous server job. The call to *sync* or *syncCollection* will block
  until synchronization is either complete or has failed with an error. The functions
  will automatically poll the slave periodically for status updates.

  The main benefit is that the connection to the slave does not need to stay open
  permanently and is thus not affected by timeout issues. Additionally the caller does
  not need to query the synchronization status from the slave manually as this is
  now performed automatically by these functions.

* fixed undefined behavior when explaining some types of AQL traversals, fixed
  display of some types of traversals in AQL explain output


v2.8.1 (2016-01-29)
-------------------

* Improved AQL Pattern matching by allowing to specify a different traversal
  direction for one or many of the edge collections.

      FOR v, e, p IN OUTBOUND @start @@ec1, INBOUND @@ec2, @@ec3

  will traverse *ec1* and *ec3* in the OUTBOUND direction and for *ec2* it will use
  the INBOUND direction. These directions can be combined in arbitrary ways, the
  direction defined after *IN [steps]* will we used as default direction and can
  be overriden for specific collections.
  This feature is only available for collection lists, it is not possible to
  combine it with graph names.

* detect more types of transaction deadlocks early

* fixed display of relational operators in traversal explain output

* fixed undefined behavior in AQL function `PARSE_IDENTIFIER`

* added "engines" field to Foxx services generated in the admin interface

* added AQL function `IS_SAME_COLLECTION`:

  *IS_SAME_COLLECTION(collection, document)*: Return true if *document* has the same
  collection id as the collection specified in *collection*. *document* can either be
  a [document handle](../Glossary/README.md#document-handle) string, or a document with
  an *_id* attribute. The function does not validate whether the collection actually
  contains the specified document, but only compares the name of the specified collection
  with the collection name part of the specified document.
  If *document* is neither an object with an *id* attribute nor a *string* value,
  the function will return *null* and raise a warning.

      /* true */
      IS_SAME_COLLECTION('_users', '_users/my-user')
      IS_SAME_COLLECTION('_users', { _id: '_users/my-user' })

      /* false */
      IS_SAME_COLLECTION('_users', 'foobar/baz')
      IS_SAME_COLLECTION('_users', { _id: 'something/else' })


v2.8.0 (2016-01-25)
-------------------

* avoid recursive locking


v2.8.0-beta8 (2016-01-19)
-------------------------

* improved internal datafile statistics for compaction and compaction triggering
  conditions, preventing excessive growth of collection datafiles under some
  workloads. This should also fix issue #1596.

* renamed AQL optimizer rule `remove-collect-into` to `remove-collect-variables`

* fixed primary and edge index lookups prematurely aborting searches when the
  specified id search value contained a different collection than the collection
  the index was created for


v2.8.0-beta7 (2016-01-06)
-------------------------

* added vm.runInThisContext

* added AQL keyword `AGGREGATE` for use in AQL `COLLECT` statement

  Using `AGGREGATE` allows more efficient aggregation (incrementally while building
  the groups) than previous versions of AQL, which built group aggregates afterwards
  from the total of all group values.

  `AGGREGATE` can be used inside a `COLLECT` statement only. If used, it must follow
  the declaration of grouping keys:

      FOR doc IN collection
        COLLECT gender = doc.gender AGGREGATE minAge = MIN(doc.age), maxAge = MAX(doc.age)
        RETURN { gender, minAge, maxAge }

  or, if no grouping keys are used, it can follow the `COLLECT` keyword:

      FOR doc IN collection
        COLLECT AGGREGATE minAge = MIN(doc.age), maxAge = MAX(doc.age)
        RETURN {
  minAge, maxAge
}

  Only specific expressions are allowed on the right-hand side of each `AGGREGATE`
  assignment:

  - on the top level the expression must be a call to one of the supported aggregation
    functions `LENGTH`, `MIN`, `MAX`, `SUM`, `AVERAGE`, `STDDEV_POPULATION`, `STDDEV_SAMPLE`,
    `VARIANCE_POPULATION`, or `VARIANCE_SAMPLE`

  - the expression must not refer to variables introduced in the `COLLECT` itself

* Foxx: mocha test paths with wildcard characters (asterisks) now work on Windows

* reserved AQL keyword `NONE` for future use

* web interface: fixed a graph display bug concerning dashboard view

* web interface: fixed several bugs during the dashboard initialize process

* web interface: included several bugfixes: #1597, #1611, #1623

* AQL query optimizer now converts `LENGTH(collection-name)` to an optimized
  expression that returns the number of documents in a collection

* adjusted the behavior of the expansion (`[*]`) operator in AQL for non-array values

  In ArangoDB 2.8, calling the expansion operator on a non-array value will always
  return an empty array. Previous versions of ArangoDB expanded non-array values by
  calling the `TO_ARRAY()` function for the value, which for example returned an
  array with a single value for boolean, numeric and string input values, and an array
  with the object's values for an object input value. This behavior was inconsistent
  with how the expansion operator works for the array indexes in 2.8, so the behavior
  is now unified:

  - if the left-hand side operand of `[*]` is an array, the array will be returned as
    is when calling `[*]` on it
  - if the left-hand side operand of `[*]` is not an array, an empty array will be
    returned by `[*]`

  AQL queries that rely on the old behavior can be changed by either calling `TO_ARRAY`
  explicitly or by using the `[*]` at the correct position.

  The following example query will change its result in 2.8 compared to 2.7:

      LET values = "foo" RETURN values[*]

  In 2.7 the query has returned the array `[ "foo" ]`, but in 2.8 it will return an
  empty array `[ ]`. To make it return the array `[ "foo" ]` again, an explicit
  `TO_ARRAY` function call is needed in 2.8 (which in this case allows the removal
  of the `[*]` operator altogether). This also works in 2.7:

      LET values = "foo" RETURN TO_ARRAY(values)

  Another example:

      LET values = [ { name: "foo" }, { name: "bar" } ]
      RETURN values[*].name[*]

  The above returned `[ [ "foo" ], [ "bar" ] ] in 2.7. In 2.8 it will return
  `[ [ ], [ ] ]`, because the value of `name` is not an array. To change the results
  to the 2.7 style, the query can be changed to

      LET values = [ { name: "foo" }, { name: "bar" } ]
      RETURN values[* RETURN TO_ARRAY(CURRENT.name)]

  The above also works in 2.7.
  The following types of queries won't change:

      LET values = [ 1, 2, 3 ] RETURN values[*]
      LET values = [ { name: "foo" }, { name: "bar" } ] RETURN values[*].name
      LET values = [ { names: [ "foo", "bar" ] }, { names: [ "baz" ] } ] RETURN values[*].names[*]
      LET values = [ { names: [ "foo", "bar" ] }, { names: [ "baz" ] } ] RETURN values[*].names[**]

* slightly adjusted V8 garbage collection strategy so that collection eventually
  happens in all contexts that hold V8 external references to documents and
  collections.

  also adjusted default value of `--javascript.gc-frequency` from 10 seconds to
  15 seconds, as less internal operations are carried out in JavaScript.

* fixes for AQL optimizer and traversal

* added `--create-collection-type` option to arangoimp
 
  This allows specifying the type of the collection to be created when 
  `--create-collection` is set to `true`. 

* Foxx export cache should no longer break if a broken app is loaded in the
  web admin interface.


v2.8.0-beta2 (2015-12-16)
-------------------------

* added AQL query optimizer rule "sort-in-values"

  This rule pre-sorts the right-hand side operand of the `IN` and `NOT IN`
  operators so the operation can use a binary search with logarithmic complexity
  instead of a linear search. The rule is applied when the right-hand side
  operand of an `IN` or `NOT IN` operator in a filter condition is a variable that
  is defined in a different loop/scope than the operator itself. Additionally,
  the filter condition must consist of solely the `IN` or `NOT IN` operation
  in order to avoid any side-effects.

* changed collection status terminology in web interface for collections for
  which an unload request has been issued from `in the process of being unloaded`
  to `will be unloaded`.

* unloading a collection via the web interface will now trigger garbage collection
  in all v8 contexts and force a WAL flush. This increases the chances of perfoming
  the unload faster.

* added the following attributes to the result of `collection.figures()` and the
  corresponding HTTP API at `PUT /_api/collection/<name>/figures`:

  - `documentReferences`: The number of references to documents in datafiles
    that JavaScript code currently holds. This information can be used for
    debugging compaction and unload issues.
  - `waitingFor`: An optional string value that contains information about
    which object type is at the head of the collection's cleanup queue. This
    information can be used for debugging compaction and unload issues.
  - `compactionStatus.time`: The point in time the compaction for the collection
    was last executed. This information can be used for debugging compaction
    issues.
  - `compactionStatus.message`: The action that was performed when the compaction
    was last run for the collection. This information can be used for debugging
    compaction issues.

  Note: `waitingFor` and `compactionStatus` may be empty when called on a coordinator
  in a cluster.

* the compaction will now provide queryable status info that can be used to track
  its progress. The compaction status is displayed in the web interface, too.

* better error reporting for arangodump and arangorestore

* arangodump will now fail by default when trying to dump edges that
  refer to already dropped collections. This can be circumvented by
  specifying the option `--force true` when invoking arangodump

* fixed cluster upgrade procedure

* the AQL functions `NEAR` and `WITHIN` now have stricter validations
  for their input parameters `limit`, `radius` and `distance`. They may now throw
  exceptions when invalid parameters are passed that may have not led
  to exceptions in previous versions.

* deprecation warnings now log stack traces

* Foxx: improved backwards compatibility with 2.5 and 2.6

  - reverted Model and Repository back to non-ES6 "classes" because of
    compatibility issues when using the extend method with a constructor

  - removed deprecation warnings for extend and controller.del

  - restored deprecated method Model.toJSONSchema

  - restored deprecated `type`, `jwt` and `sessionStorageApp` options
    in Controller#activateSessions

* Fixed a deadlock problem in the cluster


v2.8.0-beta1 (2015-12-06)
-------------------------

* added AQL function `IS_DATESTRING(value)`

  Returns true if *value* is a string that can be used in a date function.
  This includes partial dates such as *2015* or *2015-10* and strings containing
  invalid dates such as *2015-02-31*. The function will return false for all
  non-string values, even if some of them may be usable in date functions.


v2.8.0-alpha1 (2015-12-03)
--------------------------

* added AQL keywords `GRAPH`, `OUTBOUND`, `INBOUND` and `ANY` for use in graph
  traversals, reserved AQL keyword `ALL` for future use

  Usage of these keywords as collection names, variable names or attribute names
  in AQL queries will not be possible without quoting. For example, the following
  AQL query will still work as it uses a quoted collection name and a quoted
  attribute name:

      FOR doc IN `OUTBOUND`
        RETURN doc.`any`

* issue #1593: added AQL `POW` function for exponentation

* added cluster execution site info in explain output for AQL queries

* replication improvements:

  - added `autoResync` configuration parameter for continuous replication.

    When set to `true`, a replication slave will automatically trigger a full data
    re-synchronization with the master when the master cannot provide the log data
    the slave had asked for. Note that `autoResync` will only work when the option
    `requireFromPresent` is also set to `true` for the continuous replication, or
    when the continuous syncer is started and detects that no start tick is present.

    Automatic re-synchronization may transfer a lot of data from the master to the
    slave and may be expensive. It is therefore turned off by default.
    When turned off, the slave will never perform an automatic re-synchronization
    with the master.

  - added `idleMinWaitTime` and `idleMaxWaitTime` configuration parameters for
    continuous replication.

    These parameters can be used to control the minimum and maximum wait time the
    slave will (intentionally) idle and not poll for master log changes in case the
    master had sent the full logs already.
    The `idleMaxWaitTime` value will only be used when `adapativePolling` is set
    to `true`. When `adaptivePolling` is disable, only `idleMinWaitTime` will be
    used as a constant time span in which the slave will not poll the master for
    further changes. The default values are 0.5 seconds for `idleMinWaitTime` and
    2.5 seconds for `idleMaxWaitTime`, which correspond to the hard-coded values
    used in previous versions of ArangoDB.

  - added `initialSyncMaxWaitTime` configuration parameter for initial and continuous
    replication

    This option controls the maximum wait time (in seconds) that the initial
    synchronization will wait for a response from the master when fetching initial
    collection data. If no response is received within this time period, the initial
    synchronization will give up and fail. This option is also relevant for
    continuous replication in case *autoResync* is set to *true*, as then the
    continuous replication may trigger a full data re-synchronization in case
    the master cannot the log data the slave had asked for.

  - HTTP requests sent from the slave to the master during initial synchronization
    will now be retried if they fail with connection problems.

  - the initial synchronization now logs its progress so it can be queried using
    the regular replication status check APIs.

  - added `async` attribute for `sync` and `syncCollection` operations called from
    the ArangoShell. Setthing this attribute to `true` will make the synchronization
    job on the server go into the background, so that the shell does not block. The
    status of the started asynchronous synchronization job can be queried from the
    ArangoShell like this:

        /* starts initial synchronization */
        var replication = require("@arangodb/replication");
        var id = replication.sync({
          endpoint: "tcp://master.domain.org:8529",
          username: "myuser",
          password: "mypasswd",
          async: true
       });

       /* now query the id of the returned async job and print the status */
       print(replication.getSyncResult(id));

    The result of `getSyncResult()` will be `false` while the server-side job
    has not completed, and different to `false` if it has completed. When it has
    completed, all job result details will be returned by the call to `getSyncResult()`.


* fixed non-deterministic query results in some cluster queries

* fixed issue #1589

* return HTTP status code 410 (gone) instead of HTTP 408 (request timeout) for
  server-side operations that are canceled / killed. Sending 410 instead of 408
  prevents clients from re-starting the same (canceled) operation. Google Chrome
  for example sends the HTTP request again in case it is responded with an HTTP
  408, and this is exactly the opposite of the desired behavior when an operation
  is canceled / killed by the user.

* web interface: queries in AQL editor now cancelable

* web interface: dashboard - added replication information

* web interface: AQL editor now supports bind parameters

* added startup option `--server.hide-product-header` to make the server not send
  the HTTP response header `"Server: ArangoDB"` in its HTTP responses. By default,
  the option is turned off so the header is still sent as usual.

* added new AQL function `UNSET_RECURSIVE` to recursively unset attritutes from
  objects/documents

* switched command-line editor in ArangoShell and arangod to linenoise-ng

* added automatic deadlock detection for transactions

  In case a deadlock is detected, a multi-collection operation may be rolled back
  automatically and fail with error 29 (`deadlock detected`). Client code for
  operations containing more than one collection should be aware of this potential
  error and handle it accordingly, either by giving up or retrying the transaction.

* Added C++ implementations for the AQL arithmetic operations and the following
  AQL functions:
  - ABS
  - APPEND
  - COLLECTIONS
  - CURRENT_DATABASE
  - DOCUMENT
  - EDGES
  - FIRST
  - FIRST_DOCUMENT
  - FIRST_LIST
  - FLATTEN
  - FLOOR
  - FULLTEXT
  - LAST
  - MEDIAN
  - MERGE_RECURSIVE
  - MINUS
  - NEAR
  - NOT_NULL
  - NTH
  - PARSE_IDENTIFIER
  - PERCENTILE
  - POP
  - POSITION
  - PUSH
  - RAND
  - RANGE
  - REMOVE_NTH
  - REMOVE_VALUE
  - REMOVE_VALUES
  - ROUND
  - SHIFT
  - SQRT
  - STDDEV_POPULATION
  - STDDEV_SAMPLE
  - UNSHIFT
  - VARIANCE_POPULATION
  - VARIANCE_SAMPLE
  - WITHIN
  - ZIP

* improved performance of skipping over many documents in an AQL query when no
  indexes and no filters are used, e.g.

      FOR doc IN collection
        LIMIT 1000000, 10
        RETURN doc

* Added array indexes

  Hash indexes and skiplist indexes can now optionally be defined for array values
  so they index individual array members.

  To define an index for array values, the attribute name is extended with the
  expansion operator `[*]` in the index definition:

      arangosh> db.colName.ensureHashIndex("tags[*]");

  When given the following document

      { tags: [ "AQL", "ArangoDB", "Index" ] }

  the index will now contain the individual values `"AQL"`, `"ArangoDB"` and `"Index"`.

  Now the index can be used for finding all documents having `"ArangoDB"` somewhere in their
  tags array using the following AQL query:

      FOR doc IN colName
        FILTER "ArangoDB" IN doc.tags[*]
        RETURN doc

* rewrote AQL query optimizer rule `use-index-range` and renamed it to `use-indexes`.
  The name change affects rule names in the optimizer's output.

* rewrote AQL execution node `IndexRangeNode` and renamed it to `IndexNode`. The name
  change affects node names in the optimizer's explain output.

* added convenience function `db._explain(query)` for human-readable explanation
  of AQL queries

* module resolution as used by `require` now behaves more like in node.js

* the `org/arangodb/request` module now returns response bodies for error responses
  by default. The old behavior of not returning bodies for error responses can be
  re-enabled by explicitly setting the option `returnBodyOnError` to `false` (#1437)


v2.7.6 (2016-01-30)
-------------------

* detect more types of transaction deadlocks early


v2.7.5 (2016-01-22)
-------------------

* backported added automatic deadlock detection for transactions

  In case a deadlock is detected, a multi-collection operation may be rolled back
  automatically and fail with error 29 (`deadlock detected`). Client code for
  operations containing more than one collection should be aware of this potential
  error and handle it accordingly, either by giving up or retrying the transaction.

* improved internal datafile statistics for compaction and compaction triggering
  conditions, preventing excessive growth of collection datafiles under some
  workloads. This should also fix issue #1596.

* Foxx export cache should no longer break if a broken app is loaded in the
  web admin interface.

* Foxx: removed some incorrect deprecation warnings.

* Foxx: mocha test paths with wildcard characters (asterisks) now work on Windows


v2.7.4 (2015-12-21)
-------------------

* slightly adjusted V8 garbage collection strategy so that collection eventually
  happens in all contexts that hold V8 external references to documents and
  collections.

* added the following attributes to the result of `collection.figures()` and the
  corresponding HTTP API at `PUT /_api/collection/<name>/figures`:

  - `documentReferences`: The number of references to documents in datafiles
    that JavaScript code currently holds. This information can be used for
    debugging compaction and unload issues.
  - `waitingFor`: An optional string value that contains information about
    which object type is at the head of the collection's cleanup queue. This
    information can be used for debugging compaction and unload issues.
  - `compactionStatus.time`: The point in time the compaction for the collection
    was last executed. This information can be used for debugging compaction
    issues.
  - `compactionStatus.message`: The action that was performed when the compaction
    was last run for the collection. This information can be used for debugging
    compaction issues.

  Note: `waitingFor` and `compactionStatus` may be empty when called on a coordinator
  in a cluster.

* the compaction will now provide queryable status info that can be used to track
  its progress. The compaction status is displayed in the web interface, too.


v2.7.3 (2015-12-17)
-------------------

* fixed some replication value conversion issues when replication applier properties
  were set via ArangoShell

* fixed disappearing of documents for collections transferred via `sync` or
  `syncCollection` if the collection was dropped right before synchronization
  and drop and (re-)create collection markers were located in the same WAL file


* fixed an issue where overwriting the system sessions collection would break
  the web interface when authentication is enabled

v2.7.2 (2015-12-01)
-------------------

* replication improvements:

  - added `autoResync` configuration parameter for continuous replication.

    When set to `true`, a replication slave will automatically trigger a full data
    re-synchronization with the master when the master cannot provide the log data
    the slave had asked for. Note that `autoResync` will only work when the option
    `requireFromPresent` is also set to `true` for the continuous replication, or
    when the continuous syncer is started and detects that no start tick is present.

    Automatic re-synchronization may transfer a lot of data from the master to the
    slave and may be expensive. It is therefore turned off by default.
    When turned off, the slave will never perform an automatic re-synchronization
    with the master.

  - added `idleMinWaitTime` and `idleMaxWaitTime` configuration parameters for
    continuous replication.

    These parameters can be used to control the minimum and maximum wait time the
    slave will (intentionally) idle and not poll for master log changes in case the
    master had sent the full logs already.
    The `idleMaxWaitTime` value will only be used when `adapativePolling` is set
    to `true`. When `adaptivePolling` is disable, only `idleMinWaitTime` will be
    used as a constant time span in which the slave will not poll the master for
    further changes. The default values are 0.5 seconds for `idleMinWaitTime` and
    2.5 seconds for `idleMaxWaitTime`, which correspond to the hard-coded values
    used in previous versions of ArangoDB.

  - added `initialSyncMaxWaitTime` configuration parameter for initial and continuous
    replication

    This option controls the maximum wait time (in seconds) that the initial
    synchronization will wait for a response from the master when fetching initial
    collection data. If no response is received within this time period, the initial
    synchronization will give up and fail. This option is also relevant for
    continuous replication in case *autoResync* is set to *true*, as then the
    continuous replication may trigger a full data re-synchronization in case
    the master cannot the log data the slave had asked for.

  - HTTP requests sent from the slave to the master during initial synchronization
    will now be retried if they fail with connection problems.

  - the initial synchronization now logs its progress so it can be queried using
    the regular replication status check APIs.

* fixed non-deterministic query results in some cluster queries

* added missing lock instruction for primary index in compactor size calculation

* fixed issue #1589

* fixed issue #1583

* fixed undefined behavior when accessing the top level of a document with the `[*]`
  operator

* fixed potentially invalid pointer access in shaper when the currently accessed
  document got re-located by the WAL collector at the very same time

* Foxx: optional configuration options no longer log validation errors when assigned
  empty values (#1495)

* Foxx: constructors provided to Repository and Model sub-classes via extend are
  now correctly called (#1592)


v2.7.1 (2015-11-07)
-------------------

* switch to linenoise next generation

* exclude `_apps` collection from replication

  The slave has its own `_apps` collection which it populates on server start.
  When replicating data from the master to the slave, the data from the master may
  clash with the slave's own data in the `_apps` collection. Excluding the `_apps`
  collection from replication avoids this.

* disable replication appliers when starting in modes `--upgrade`, `--no-server`
  and `--check-upgrade`

* more detailed output in arango-dfdb

* fixed "no start tick" issue in replication applier

  This error could occur after restarting a slave server after a shutdown
  when no data was ever transferred from the master to the slave via the
  continuous replication

* fixed problem during SSL client connection abort that led to scheduler thread
  staying at 100% CPU saturation

* fixed potential segfault in AQL `NEIGHBORS` function implementation when C++ function
  variant was used and collection names were passed as strings

* removed duplicate target for some frontend JavaScript files from the Makefile

* make AQL function `MERGE()` work on a single array parameter, too.
  This allows combining the attributes of multiple objects from an array into
  a single object, e.g.

      RETURN MERGE([
        { foo: 'bar' },
        { quux: 'quetzalcoatl', ruled: true },
        { bar: 'baz', foo: 'done' }
      ])

  will now return:

      {
        "foo": "done",
        "quux": "quetzalcoatl",
        "ruled": true,
        "bar": "baz"
      }

* fixed potential deadlock in collection status changing on Windows

* fixed hard-coded `incremental` parameter in shell implementation of
  `syncCollection` function in replication module

* fix for GCC5: added check for '-stdlib' option


v2.7.0 (2015-10-09)
-------------------

* fixed request statistics aggregation
  When arangod was started in supervisor mode, the request statistics always showed
  0 requests, as the statistics aggregation thread did not run then.

* read server configuration files before dropping privileges. this ensures that
  the SSL keyfile specified in the configuration can be read with the server's start
  privileges (i.e. root when using a standard ArangoDB package).

* fixed replication with a 2.6 replication configuration and issues with a 2.6 master

* raised default value of `--server.descriptors-minimum` to 1024

* allow Foxx apps to be installed underneath URL path `/_open/`, so they can be
  (intentionally) accessed without authentication.

* added *allowImplicit* sub-attribute in collections declaration of transactions.
  The *allowImplicit* attributes allows making transactions fail should they
  read-access a collection that was not explicitly declared in the *collections*
  array of the transaction.

* added "special" password ARANGODB_DEFAULT_ROOT_PASSWORD. If you pass
  ARANGODB_DEFAULT_ROOT_PASSWORD as password, it will read the password
  from the environment variable ARANGODB_DEFAULT_ROOT_PASSWORD


v2.7.0-rc2 (2015-09-22)
-----------------------

* fix over-eager datafile compaction

  This should reduce the need to compact directly after loading a collection when a
  collection datafile contained many insertions and updates for the same documents. It
  should also prevent from re-compacting already merged datafiles in case not many
  changes were made. Compaction will also make fewer index lookups than before.

* added `syncCollection()` function in module `org/arangodb/replication`

  This allows synchronizing the data of a single collection from a master to a slave
  server. Synchronization can either restore the whole collection by transferring all
  documents from the master to the slave, or incrementally by only transferring documents
  that differ. This is done by partitioning the collection's entire key space into smaller
  chunks and comparing the data chunk-wise between master and slave. Only chunks that are
  different will be re-transferred.

  The `syncCollection()` function can be used as follows:

      require("org/arangodb/replication").syncCollection(collectionName, options);

  e.g.

      require("org/arangodb/replication").syncCollection("myCollection", {
        endpoint: "tcp://127.0.0.1:8529",  /* master */
        username: "root",                  /* username for master */
        password: "secret",                /* password for master */
        incremental: true                  /* use incremental mode */
      });


* additionally allow the following characters in document keys:

  `(` `)` `+` `,` `=` `;` `$` `!` `*` `'` `%`


v2.7.0-rc1 (2015-09-17)
-----------------------

* removed undocumented server-side-only collection functions:
  * collection.OFFSET()
  * collection.NTH()
  * collection.NTH2()
  * collection.NTH3()

* upgraded Swagger to version 2.0 for the Documentation

  This gives the user better prepared test request structures.
  More conversions will follow so finally client libraries can be auto-generated.

* added extra AQL functions for date and time calculation and manipulation.
  These functions were contributed by GitHub users @CoDEmanX and @friday.
  A big thanks for their work!

  The following extra date functions are available from 2.7 on:

  * `DATE_DAYOFYEAR(date)`: Returns the day of year number of *date*.
    The return values range from 1 to 365, or 366 in a leap year respectively.

  * `DATE_ISOWEEK(date)`: Returns the ISO week date of *date*.
    The return values range from 1 to 53. Monday is considered the first day of the week.
    There are no fractional weeks, thus the last days in December may belong to the first
    week of the next year, and the first days in January may be part of the previous year's
    last week.

  * `DATE_LEAPYEAR(date)`: Returns whether the year of *date* is a leap year.

  * `DATE_QUARTER(date)`: Returns the quarter of the given date (1-based):
    * 1: January, February, March
    * 2: April, May, June
    * 3: July, August, September
    * 4: October, November, December

  - *DATE_DAYS_IN_MONTH(date)*: Returns the number of days in *date*'s month (28..31).

  * `DATE_ADD(date, amount, unit)`: Adds *amount* given in *unit* to *date* and
    returns the calculated date.

    *unit* can be either of the following to specify the time unit to add or
    subtract (case-insensitive):
    - y, year, years
    - m, month, months
    - w, week, weeks
    - d, day, days
    - h, hour, hours
    - i, minute, minutes
    - s, second, seconds
    - f, millisecond, milliseconds

    *amount* is the number of *unit*s to add (positive value) or subtract
    (negative value).

  * `DATE_SUBTRACT(date, amount, unit)`: Subtracts *amount* given in *unit* from
    *date* and returns the calculated date.

    It works the same as `DATE_ADD()`, except that it subtracts. It is equivalent
    to calling `DATE_ADD()` with a negative amount, except that `DATE_SUBTRACT()`
    can also subtract ISO durations. Note that negative ISO durations are not
    supported (i.e. starting with `-P`, like `-P1Y`).

  * `DATE_DIFF(date1, date2, unit, asFloat)`: Calculate the difference
    between two dates in given time *unit*, optionally with decimal places.
    Returns a negative value if *date1* is greater than *date2*.

  * `DATE_COMPARE(date1, date2, unitRangeStart, unitRangeEnd)`: Compare two
    partial dates and return true if they match, false otherwise. The parts to
    compare are defined by a range of time units.

    The full range is: years, months, days, hours, minutes, seconds, milliseconds.
    Pass the unit to start from as *unitRangeStart*, and the unit to end with as
    *unitRangeEnd*. All units in between will be compared. Leave out *unitRangeEnd*
    to only compare *unitRangeStart*.

  * `DATE_FORMAT(date, format)`: Format a date according to the given format string.
    It supports the following placeholders (case-insensitive):
    - %t: timestamp, in milliseconds since midnight 1970-01-01
    - %z: ISO date (0000-00-00T00:00:00.000Z)
    - %w: day of week (0..6)
    - %y: year (0..9999)
    - %yy: year (00..99), abbreviated (last two digits)
    - %yyyy: year (0000..9999), padded to length of 4
    - %yyyyyy: year (-009999 .. +009999), with sign prefix and padded to length of 6
    - %m: month (1..12)
    - %mm: month (01..12), padded to length of 2
    - %d: day (1..31)
    - %dd: day (01..31), padded to length of 2
    - %h: hour (0..23)
    - %hh: hour (00..23), padded to length of 2
    - %i: minute (0..59)
    - %ii: minute (00..59), padded to length of 2
    - %s: second (0..59)
    - %ss: second (00..59), padded to length of 2
    - %f: millisecond (0..999)
    - %fff: millisecond (000..999), padded to length of 3
    - %x: day of year (1..366)
    - %xxx: day of year (001..366), padded to length of 3
    - %k: ISO week date (1..53)
    - %kk: ISO week date (01..53), padded to length of 2
    - %l: leap year (0 or 1)
    - %q: quarter (1..4)
    - %a: days in month (28..31)
    - %mmm: abbreviated English name of month (Jan..Dec)
    - %mmmm: English name of month (January..December)
    - %www: abbreviated English name of weekday (Sun..Sat)
    - %wwww: English name of weekday (Sunday..Saturday)
    - %&: special escape sequence for rare occasions
    - %%: literal %
    - %: ignored

* new WAL logfiles and datafiles are now created non-sparse

  This prevents SIGBUS signals being raised when memory of a sparse datafile is accessed
  and the disk is full and the accessed file part is not actually disk-backed. In
  this case the mapped memory region is not necessarily backed by physical memory, and
  accessing the memory may raise SIGBUS and crash arangod.

* the `internal.download()` function and the module `org/arangodb/request` used some
  internal library function that handled the sending of HTTP requests from inside of
  ArangoDB. This library unconditionally set an HTTP header `Accept-Encoding: gzip`
  in all outgoing HTTP requests.

  This has been fixed in 2.7, so `Accept-Encoding: gzip` is not set automatically anymore.
  Additionally, the header `User-Agent: ArangoDB` is not set automatically either. If
  client applications desire to send these headers, they are free to add it when
  constructing the requests using the `download` function or the request module.

* fixed issue #1436: org/arangodb/request advertises deflate without supporting it

* added template string generator function `aqlQuery` for generating AQL queries

  This can be used to generate safe AQL queries with JavaScript parameter
  variables or expressions easily:

      var name = 'test';
      var attributeName = '_key';
      var query = aqlQuery`FOR u IN users FILTER u.name == ${name} RETURN u.${attributeName}`;
      db._query(query);

* report memory usage for document header data (revision id, pointer to data etc.)
  in `db.collection.figures()`. The memory used for document headers will now
  show up in the already existing attribute `indexes.size`. Due to that, the index
  sizes reported by `figures()` in 2.7 will be higher than those reported by 2.6,
  but the 2.7 values are more accurate.

* IMPORTANT CHANGE: the filenames in dumps created by arangodump now contain
  not only the name of the dumped collection, but also an additional 32-digit hash
  value. This is done to prevent overwriting dump files in case-insensitive file
  systems when there exist multiple collections with the same name (but with
  different cases).

  For example, if a database has two collections: `test` and `Test`, previous
  versions of ArangoDB created the files

  * `test.structure.json` and `test.data.json` for collection `test`
  * `Test.structure.json` and `Test.data.json` for collection `Test`

  This did not work for case-insensitive filesystems, because the files for the
  second collection would have overwritten the files of the first. arangodump in
  2.7 will create the following filenames instead:

  * `test_098f6bcd4621d373cade4e832627b4f6.structure.json` and `test_098f6bcd4621d373cade4e832627b4f6.data.json`
  * `Test_0cbc6611f5540bd0809a388dc95a615b.structure.json` and `Test_0cbc6611f5540bd0809a388dc95a615b.data.json`

  These filenames will be unambiguous even in case-insensitive filesystems.

* IMPORTANT CHANGE: make arangod actually close lingering client connections
  when idle for at least the duration specified via `--server.keep-alive-timeout`.
  In previous versions of ArangoDB, connections were not closed by the server
  when the timeout was reached and the client was still connected. Now the
  connection is properly closed by the server in case of timeout. Client
  applications relying on the old behavior may now need to reconnect to the
  server when their idle connections time out and get closed (note: connections
  being idle for a long time may be closed by the OS or firewalls anyway -
  client applications should be aware of that and try to reconnect).

* IMPORTANT CHANGE: when starting arangod, the server will drop the process
  privileges to the specified values in options `--server.uid` and `--server.gid`
  instantly after parsing the startup options.

  That means when either `--server.uid` or `--server.gid` are set, the privilege
  change will happen earlier. This may prevent binding the server to an endpoint
  with a port number lower than 1024 if the arangodb user has no privileges
  for that. Previous versions of ArangoDB changed the privileges later, so some
  startup actions were still carried out under the invoking user (i.e. likely
  *root* when started via init.d or system scripts) and especially binding to
  low port numbers was still possible there.

  The default privileges for user *arangodb* will not be sufficient for binding
  to port numbers lower than 1024. To have an ArangoDB 2.7 bind to a port number
  lower than 1024, it needs to be started with either a different privileged user,
  or the privileges of the *arangodb* user have to raised manually beforehand.

* added AQL optimizer rule `patch-update-statements`

* Linux startup scripts and systemd configuration for arangod now try to
  adjust the NOFILE (number of open files) limits for the process. The limit
  value is set to 131072 (128k) when ArangoDB is started via start/stop
  commands

* When ArangoDB is started/stopped manually via the start/stop commands, the
  main process will wait for up to 10 seconds after it forks the supervisor
  and arangod child processes. If the startup fails within that period, the
  start/stop script will fail with an exit code other than zero. If the
  startup of the supervisor or arangod is still ongoing after 10 seconds,
  the main program will still return with exit code 0. The limit of 10 seconds
  is arbitrary because the time required for a startup is not known in advance.

* added startup option `--database.throw-collection-not-loaded-error`

  Accessing a not-yet loaded collection will automatically load a collection
  on first access. This flag controls what happens in case an operation
  would need to wait for another thread to finalize loading a collection. If
  set to *true*, then the first operation that accesses an unloaded collection
  will load it. Further threads that try to access the same collection while
  it is still loading immediately fail with an error (1238, *collection not loaded*).
  This is to prevent all server threads from being blocked while waiting on the
  same collection to finish loading. When the first thread has completed loading
  the collection, the collection becomes regularly available, and all operations
  from that point on can be carried out normally, and error 1238 will not be
  thrown anymore for that collection.

  If set to *false*, the first thread that accesses a not-yet loaded collection
  will still load it. Other threads that try to access the collection while
  loading will not fail with error 1238 but instead block until the collection
  is fully loaded. This configuration might lead to all server threads being
  blocked because they are all waiting for the same collection to complete
  loading. Setting the option to *true* will prevent this from happening, but
  requires clients to catch error 1238 and react on it (maybe by scheduling
  a retry for later).

  The default value is *false*.

* added better control-C support in arangosh

  When CTRL-C is pressed in arangosh, it will now print a `^C` first. Pressing
  CTRL-C again will reset the prompt if something was entered before, or quit
  arangosh if no command was entered directly before.

  This affects the arangosh version build with Readline-support only (Linux
  and MacOS).

  The MacOS version of ArangoDB for Homebrew now depends on Readline, too. The
  Homebrew formula has been changed accordingly.
  When self-compiling ArangoDB on MacOS without Homebrew, Readline now is a
  prerequisite.

* increased default value for collection-specific `indexBuckets` value from 1 to 8

  Collections created from 2.7 on will use the new default value of `8` if not
  overridden on collection creation or later using
  `collection.properties({ indexBuckets: ... })`.

  The `indexBuckets` value determines the number of buckets to use for indexes of
  type `primary`, `hash` and `edge`. Having multiple index buckets allows splitting
  an index into smaller components, which can be filled in parallel when a collection
  is loading. Additionally, resizing and reallocation of indexes are faster and
  less intrusive if the index uses multiple buckets, because resize and reallocation
  will affect only data in a single bucket instead of all index values.

  The index buckets will be filled in parallel when loading a collection if the collection
  has an `indexBuckets` value greater than 1 and the collection contains a significant
  amount of documents/edges (the current threshold is 256K documents but this value
  may change in future versions of ArangoDB).

* changed HTTP client to use poll instead of select on Linux and MacOS

  This affects the ArangoShell and user-defined JavaScript code running inside
  arangod that initiates its own HTTP calls.

  Using poll instead of select allows using arbitrary high file descriptors
  (bigger than the compiled in FD_SETSIZE). Server connections are still handled using
  epoll, which has never been affected by FD_SETSIZE.

* implemented AQL `LIKE` function using ICU regexes

* added `RETURN DISTINCT` for AQL queries to return unique results:

      FOR doc IN collection
        RETURN DISTINCT doc.status

  This change also introduces `DISTINCT` as an AQL keyword.

* removed `createNamedQueue()` and `addJob()` functions from org/arangodb/tasks

* use less locks and more atomic variables in the internal dispatcher
  and V8 context handling implementations. This leads to improved throughput in
  some ArangoDB internals and allows for higher HTTP request throughput for
  many operations.

  A short overview of the improvements can be found here:

  https://www.arangodb.com/2015/08/throughput-enhancements/

* added shorthand notation for attribute names in AQL object literals:

      LET name = "Peter"
      LET age = 42
      RETURN { name, age }

  The above is the shorthand equivalent of the generic form

      LET name = "Peter"
      LET age = 42
      RETURN { name : name, age : age }

* removed configure option `--enable-timings`

  This option did not have any effect.

* removed configure option `--enable-figures`

  This option previously controlled whether HTTP request statistics code was
  compiled into ArangoDB or not. The previous default value was `true` so
  statistics code was available in official packages. Setting the option to
  `false` led to compile errors so it is doubtful the default value was
  ever changed. By removing the option some internal statistics code was also
  simplified.

* removed run-time manipulation methods for server endpoints:

  * `db._removeEndpoint()`
  * `db._configureEndpoint()`
  * HTTP POST `/_api/endpoint`
  * HTTP DELETE `/_api/endpoint`

* AQL query result cache

  The query result cache can optionally cache the complete results of all or selected AQL queries.
  It can be operated in the following modes:

  * `off`: the cache is disabled. No query results will be stored
  * `on`: the cache will store the results of all AQL queries unless their `cache`
    attribute flag is set to `false`
  * `demand`: the cache will store the results of AQL queries that have their
    `cache` attribute set to `true`, but will ignore all others

  The mode can be set at server startup using the `--database.query-cache-mode` configuration
  option and later changed at runtime.

  The following HTTP REST APIs have been added for controlling the query cache:

  * HTTP GET `/_api/query-cache/properties`: returns the global query cache configuration
  * HTTP PUT `/_api/query-cache/properties`: modifies the global query cache configuration
  * HTTP DELETE `/_api/query-cache`: invalidates all results in the query cache

  The following JavaScript functions have been added for controlling the query cache:

  * `require("org/arangodb/aql/cache").properties()`: returns the global query cache configuration
  * `require("org/arangodb/aql/cache").properties(properties)`: modifies the global query cache configuration
  * `require("org/arangodb/aql/cache").clear()`: invalidates all results in the query cache

* do not link arangoimp against V8

* AQL function call arguments optimization

  This will lead to arguments in function calls inside AQL queries not being copied but passed
  by reference. This may speed up calls to functions with bigger argument values or queries that
  call functions a lot of times.

* upgraded V8 version to 4.3.61

* removed deprecated AQL `SKIPLIST` function.

  This function was introduced in older versions of ArangoDB with a less powerful query optimizer to
  retrieve data from a skiplist index using a `LIMIT` clause. It was marked as deprecated in ArangoDB
  2.6.

  Since ArangoDB 2.3 the behavior of the `SKIPLIST` function can be emulated using regular AQL
  constructs, e.g.

      FOR doc IN @@collection
        FILTER doc.value >= @value
        SORT doc.value DESC
        LIMIT 1
        RETURN doc

* the `skip()` function for simple queries does not accept negative input any longer.
  This feature was deprecated in 2.6.0.

* fix exception handling

  In some cases JavaScript exceptions would re-throw without information of the original problem.
  Now the original exception is logged for failure analysis.

* based REST API method PUT `/_api/simple/all` on the cursor API and make it use AQL internally.

  The change speeds up this REST API method and will lead to additional query information being
  returned by the REST API. Clients can use this extra information or ignore it.

* Foxx Queue job success/failure handlers arguments have changed from `(jobId, jobData, result, jobFailures)` to `(result, jobData, job)`.

* added Foxx Queue job options `repeatTimes`, `repeatUntil` and `repeatDelay` to automatically re-schedule jobs when they are completed.

* added Foxx manifest configuration type `password` to mask values in the web interface.

* fixed default values in Foxx manifest configurations sometimes not being used as defaults.

* fixed optional parameters in Foxx manifest configurations sometimes not being cleared correctly.

* Foxx dependencies can now be marked as optional using a slightly more verbose syntax in your manifest file.

* converted Foxx constructors to ES6 classes so you can extend them using class syntax.

* updated aqb to 2.0.

* updated chai to 3.0.

* Use more madvise calls to speed up things when memory is tight, in particular
  at load time but also for random accesses later.

* Overhauled web interface

  The web interface now has a new design.

  The API documentation for ArangoDB has been moved from "Tools" to "Links" in the web interface.

  The "Applications" tab in the web interfaces has been renamed to "Services".


v2.6.12 (2015-12-02)
--------------------

* fixed disappearing of documents for collections transferred via `sync` if the
  the collection was dropped right before synchronization and drop and (re-)create
  collection markers were located in the same WAL file

* added missing lock instruction for primary index in compactor size calculation

* fixed issue #1589

* fixed issue #1583

* Foxx: optional configuration options no longer log validation errors when assigned
  empty values (#1495)


v2.6.11 (2015-11-18)
--------------------

* fixed potentially invalid pointer access in shaper when the currently accessed
  document got re-located by the WAL collector at the very same time


v2.6.10 (2015-11-10)
--------------------

* disable replication appliers when starting in modes `--upgrade`, `--no-server`
  and `--check-upgrade`

* more detailed output in arango-dfdb

* fixed potential deadlock in collection status changing on Windows

* issue #1521: Can't dump/restore with user and password


v2.6.9 (2015-09-29)
-------------------

* added "special" password ARANGODB_DEFAULT_ROOT_PASSWORD. If you pass
  ARANGODB_DEFAULT_ROOT_PASSWORD as password, it will read the password
  from the environment variable ARANGODB_DEFAULT_ROOT_PASSWORD

* fixed failing AQL skiplist, sort and limit combination

  When using a Skiplist index on an attribute (say "a") and then using sort
  and skip on this attribute caused the result to be empty e.g.:

    require("internal").db.test.ensureSkiplist("a");
    require("internal").db._query("FOR x IN test SORT x.a LIMIT 10, 10");

  Was always empty no matter how many documents are stored in test.
  This is now fixed.

v2.6.8 (2015-09-09)
-------------------

* ARM only:

  The ArangoDB packages for ARM require the kernel to allow unaligned memory access.
  How the kernel handles unaligned memory access is configurable at runtime by
  checking and adjusting the contents `/proc/cpu/alignment`.

  In order to operate on ARM, ArangoDB requires the bit 1 to be set. This will
  make the kernel trap and adjust unaligned memory accesses. If this bit is not
  set, the kernel may send a SIGBUS signal to ArangoDB and terminate it.

  To set bit 1 in `/proc/cpu/alignment` use the following command as a privileged
  user (e.g. root):

      echo "2" > /proc/cpu/alignment

  Note that this setting affects all user processes and not just ArangoDB. Setting
  the alignment with the above command will also not make the setting permanent,
  so it will be lost after a restart of the system. In order to make the setting
  permanent, it should be executed during system startup or before starting arangod.

  The ArangoDB start/stop scripts do not adjust the alignment setting, but rely on
  the environment to have the correct alignment setting already. The reason for this
  is that the alignment settings also affect all other user processes (which ArangoDB
  is not aware of) and thus may have side-effects outside of ArangoDB. It is therefore
  more reasonable to have the system administrator carry out the change.


v2.6.7 (2015-08-25)
-------------------

* improved AssocMulti index performance when resizing.

  This makes the edge index perform less I/O when under memory pressure.


v2.6.6 (2015-08-23)
-------------------

* added startup option `--server.additional-threads` to create separate queues
  for slow requests.


v2.6.5 (2015-08-17)
-------------------

* added startup option `--database.throw-collection-not-loaded-error`

  Accessing a not-yet loaded collection will automatically load a collection
  on first access. This flag controls what happens in case an operation
  would need to wait for another thread to finalize loading a collection. If
  set to *true*, then the first operation that accesses an unloaded collection
  will load it. Further threads that try to access the same collection while
  it is still loading immediately fail with an error (1238, *collection not loaded*).
  This is to prevent all server threads from being blocked while waiting on the
  same collection to finish loading. When the first thread has completed loading
  the collection, the collection becomes regularly available, and all operations
  from that point on can be carried out normally, and error 1238 will not be
  thrown anymore for that collection.

  If set to *false*, the first thread that accesses a not-yet loaded collection
  will still load it. Other threads that try to access the collection while
  loading will not fail with error 1238 but instead block until the collection
  is fully loaded. This configuration might lead to all server threads being
  blocked because they are all waiting for the same collection to complete
  loading. Setting the option to *true* will prevent this from happening, but
  requires clients to catch error 1238 and react on it (maybe by scheduling
  a retry for later).

  The default value is *false*.

* fixed busy wait loop in scheduler threads that sometimes consumed 100% CPU while
  waiting for events on connections closed unexpectedly by the client side

* handle attribute `indexBuckets` when restoring collections via arangorestore.
  Previously the `indexBuckets` attribute value from the dump was ignored, and the
   server default value for `indexBuckets` was used when restoring a collection.

* fixed "EscapeValue already set error" crash in V8 actions that might have occurred when
  canceling V8-based operations.


v2.6.4 (2015-08-01)
-------------------

* V8: Upgrade to version 4.1.0.27 - this is intended to be the stable V8 version.

* fixed issue #1424: Arango shell should not processing arrows pushing on keyboard


v2.6.3 (2015-07-21)
-------------------

* issue #1409: Document values with null character truncated


v2.6.2 (2015-07-04)
-------------------

* fixed issue #1383: bindVars for HTTP API doesn't work with empty string

* fixed handling of default values in Foxx manifest configurations

* fixed handling of optional parameters in Foxx manifest configurations

* fixed a reference error being thrown in Foxx queues when a function-based job type is used that is not available and no options object is passed to queue.push


v2.6.1 (2015-06-24)
-------------------

* Add missing swagger files to cmake build. fixes #1368

* fixed documentation errors


v2.6.0 (2015-06-20)
-------------------

* using negative values for `SimpleQuery.skip()` is deprecated.
  This functionality will be removed in future versions of ArangoDB.

* The following simple query functions are now deprecated:

  * collection.near
  * collection.within
  * collection.geo
  * collection.fulltext
  * collection.range
  * collection.closedRange

  This also lead to the following REST API methods being deprecated from now on:

  * PUT /_api/simple/near
  * PUT /_api/simple/within
  * PUT /_api/simple/fulltext
  * PUT /_api/simple/range

  It is recommended to replace calls to these functions or APIs with equivalent AQL queries,
  which are more flexible because they can be combined with other operations:

      FOR doc IN NEAR(@@collection, @latitude, @longitude, @limit)
        RETURN doc

      FOR doc IN WITHIN(@@collection, @latitude, @longitude, @radius, @distanceAttributeName)
        RETURN doc

      FOR doc IN FULLTEXT(@@collection, @attributeName, @queryString, @limit)
        RETURN doc

      FOR doc IN @@collection
        FILTER doc.value >= @left && doc.value < @right
        LIMIT @skip, @limit
        RETURN doc`

  The above simple query functions and REST API methods may be removed in future versions
  of ArangoDB.

* deprecated now-obsolete AQL `SKIPLIST` function

  The function was introduced in older versions of ArangoDB with a less powerful query optimizer to
  retrieve data from a skiplist index using a `LIMIT` clause.

  Since 2.3 the same goal can be achieved by using regular AQL constructs, e.g.

      FOR doc IN collection FILTER doc.value >= @value SORT doc.value DESC LIMIT 1 RETURN doc

* fixed issues when switching the database inside tasks and during shutdown of database cursors

  These features were added during 2.6 alpha stage so the fixes affect devel/2.6-alpha builds only

* issue #1360: improved foxx-manager help

* added `--enable-tcmalloc` configure option.

  When this option is set, arangod and the client tools will be linked against tcmalloc, which replaces
  the system allocator. When the option is set, a tcmalloc library must be present on the system under
  one of the names `libtcmalloc`, `libtcmalloc_minimal` or `libtcmalloc_debug`.

  As this is a configure option, it is supported for manual builds on Linux-like systems only. tcmalloc
  support is currently experimental.

* issue #1353: Windows: HTTP API - incorrect path in errorMessage

* issue #1347: added option `--create-database` for arangorestore.

  Setting this option to `true` will now create the target database if it does not exist. When creating
  the target database, the username and passwords passed to arangorestore will be used to create an
  initial user for the new database.

* issue #1345: advanced debug information for User Functions

* issue #1341: Can't use bindvars in UPSERT

* fixed vulnerability in JWT implementation.

* changed default value of option `--database.ignore-datafile-errors` from `true` to `false`

  If the new default value of `false` is used, then arangod will refuse loading collections that contain
  datafiles with CRC mismatches or other errors. A collection with datafile errors will then become
  unavailable. This prevents follow up errors from happening.

  The only way to access such collection is to use the datafile debugger (arango-dfdb) and try to repair
  or truncate the datafile with it.

  If `--database.ignore-datafile-errors` is set to `true`, then collections will become available
  even if parts of their data cannot be loaded. This helps availability, but may cause (partial) data
  loss and follow up errors.

* added server startup option `--server.session-timeout` for controlling the timeout of user sessions
  in the web interface

* add sessions and cookie authentication for ArangoDB's web interface

  ArangoDB's built-in web interface now uses sessions. Session information ids are stored in cookies,
  so clients using the web interface must accept cookies in order to use it

* web interface: display query execution time in AQL editor

* web interface: renamed AQL query *submit* button to *execute*

* web interface: added query explain feature in AQL editor

* web interface: demo page added. only working if demo data is available, hidden otherwise

* web interface: added support for custom app scripts with optional arguments and results

* web interface: mounted apps that need to be configured are now indicated in the app overview

* web interface: added button for running tests to app details

* web interface: added button for configuring app dependencies to app details

* web interface: upgraded API documentation to use Swagger 2

* INCOMPATIBLE CHANGE

  removed startup option `--log.severity`

  The docs for `--log.severity` mentioned lots of severities (e.g. `exception`, `technical`, `functional`, `development`)
  but only a few severities (e.g. `all`, `human`) were actually used, with `human` being the default and `all` enabling the
  additional logging of requests. So the option pretended to control a lot of things which it actually didn't. Additionally,
  the option `--log.requests-file` was around for a long time already, also controlling request logging.

  Because the `--log.severity` option effectively did not control that much, it was removed. A side effect of removing the
  option is that 2.5 installations which used `--log.severity all` will not log requests after the upgrade to 2.6. This can
  be adjusted by setting the `--log.requests-file` option.

* add backtrace to fatal log events

* added optional `limit` parameter for AQL function `FULLTEXT`

* make fulltext index also index text values contained in direct sub-objects of the indexed
  attribute.

  Previous versions of ArangoDB only indexed the attribute value if it was a string. Sub-attributes
  of the index attribute were ignored when fulltext indexing.

  Now, if the index attribute value is an object, the object's values will each be included in the
  fulltext index if they are strings. If the index attribute value is an array, the array's values
  will each be included in the fulltext index if they are strings.

  For example, with a fulltext index present on the `translations` attribute, the following text
  values will now be indexed:

      var c = db._create("example");
      c.ensureFulltextIndex("translations");
      c.insert({ translations: { en: "fox", de: "Fuchs", fr: "renard", ru: "лиса" } });
      c.insert({ translations: "Fox is the English translation of the German word Fuchs" });
      c.insert({ translations: [ "ArangoDB", "document", "database", "Foxx" ] });

      c.fulltext("translations", "лиса").toArray();       // returns only first document
      c.fulltext("translations", "Fox").toArray();        // returns first and second documents
      c.fulltext("translations", "prefix:Fox").toArray(); // returns all three documents

* added batch document removal and lookup commands:

      collection.lookupByKeys(keys)
      collection.removeByKeys(keys)

  These commands can be used to perform multi-document lookup and removal operations efficiently
  from the ArangoShell. The argument to these operations is an array of document keys.

  Also added HTTP APIs for batch document commands:

  * PUT /_api/simple/lookup-by-keys
  * PUT /_api/simple/remove-by-keys

* properly prefix document address URLs with the current database name for calls to the REST
  API method GET `/_api/document?collection=...` (that method will return partial URLs to all
  documents in the collection).

  Previous versions of ArangoDB returned the URLs starting with `/_api/` but without the current
  database name, e.g. `/_api/document/mycollection/mykey`. Starting with 2.6, the response URLs
  will include the database name as well, e.g. `/_db/_system/_api/document/mycollection/mykey`.

* added dedicated collection export HTTP REST API

  ArangoDB now provides a dedicated collection export API, which can take snapshots of entire
  collections more efficiently than the general-purpose cursor API. The export API is useful
  to transfer the contents of an entire collection to a client application. It provides optional
  filtering on specific attributes.

  The export API is available at endpoint `POST /_api/export?collection=...`. The API has the
  same return value structure as the already established cursor API (`POST /_api/cursor`).

  An introduction to the export API is given in this blog post:
  http://jsteemann.github.io/blog/2015/04/04/more-efficient-data-exports/

* subquery optimizations for AQL queries

  This optimization avoids copying intermediate results into subqueries that are not required
  by the subquery.

  A brief description can be found here:
  http://jsteemann.github.io/blog/2015/05/04/subquery-optimizations/

* return value optimization for AQL queries

  This optimization avoids copying the final query result inside the query's main `ReturnNode`.

  A brief description can be found here:
  http://jsteemann.github.io/blog/2015/05/04/return-value-optimization-for-aql/

* speed up AQL queries containing big `IN` lists for index lookups

  `IN` lists used for index lookups had performance issues in previous versions of ArangoDB.
  These issues have been addressed in 2.6 so using bigger `IN` lists for filtering is much
  faster.

  A brief description can be found here:
  http://jsteemann.github.io/blog/2015/05/07/in-list-improvements/

* allow `@` and `.` characters in document keys, too

  This change also leads to document keys being URL-encoded when returned in HTTP `location`
  response headers.

* added alternative implementation for AQL COLLECT

  The alternative method uses a hash table for grouping and does not require its input elements
  to be sorted. It will be taken into account by the optimizer for `COLLECT` statements that do
  not use an `INTO` clause.

  In case a `COLLECT` statement can use the hash table variant, the optimizer will create an extra
  plan for it at the beginning of the planning phase. In this plan, no extra `SORT` node will be
  added in front of the `COLLECT` because the hash table variant of `COLLECT` does not require
  sorted input. Instead, a `SORT` node will be added after it to sort its output. This `SORT` node
  may be optimized away again in later stages. If the sort order of the result is irrelevant to
  the user, adding an extra `SORT null` after a hash `COLLECT` operation will allow the optimizer to
  remove the sorts altogether.

  In addition to the hash table variant of `COLLECT`, the optimizer will modify the original plan
  to use the regular `COLLECT` implementation. As this implementation requires sorted input, the
  optimizer will insert a `SORT` node in front of the `COLLECT`. This `SORT` node may be optimized
  away in later stages.

  The created plans will then be shipped through the regular optimization pipeline. In the end,
  the optimizer will pick the plan with the lowest estimated total cost as usual. The hash table
  variant does not require an up-front sort of the input, and will thus be preferred over the
  regular `COLLECT` if the optimizer estimates many input elements for the `COLLECT` node and
  cannot use an index to sort them.

  The optimizer can be explicitly told to use the regular *sorted* variant of `COLLECT` by
  suffixing a `COLLECT` statement with `OPTIONS { "method" : "sorted" }`. This will override the
  optimizer guesswork and only produce the *sorted* variant of `COLLECT`.

  A blog post on the new `COLLECT` implementation can be found here:
  http://jsteemann.github.io/blog/2015/04/22/collecting-with-a-hash-table/

* refactored HTTP REST API for cursors

  The HTTP REST API for cursors (`/_api/cursor`) has been refactored to improve its performance
  and use less memory.

  A post showing some of the performance improvements can be found here:
  http://jsteemann.github.io/blog/2015/04/01/improvements-for-the-cursor-api/

* simplified return value syntax for data-modification AQL queries

  ArangoDB 2.4 since version allows to return results from data-modification AQL queries. The
  syntax for this was quite limited and verbose:

      FOR i IN 1..10
        INSERT { value: i } IN test
        LET inserted = NEW
        RETURN inserted

  The `LET inserted = NEW RETURN inserted` was required literally to return the inserted
  documents. No calculations could be made using the inserted documents.

  This is now more flexible. After a data-modification clause (e.g. `INSERT`, `UPDATE`, `REPLACE`,
  `REMOVE`, `UPSERT`) there can follow any number of `LET` calculations. These calculations can
  refer to the pseudo-values `OLD` and `NEW` that are created by the data-modification statements.

  This allows returning projections of inserted or updated documents, e.g.:

      FOR i IN 1..10
        INSERT { value: i } IN test
        RETURN { _key: NEW._key, value: i }

  Still not every construct is allowed after a data-modification clause. For example, no functions
  can be called that may access documents.

  More information can be found here:
  http://jsteemann.github.io/blog/2015/03/27/improvements-for-data-modification-queries/

* added AQL `UPSERT` statement

  This adds an `UPSERT` statement to AQL that is a combination of both `INSERT` and `UPDATE` /
  `REPLACE`. The `UPSERT` will search for a matching document using a user-provided example.
  If no document matches the example, the *insert* part of the `UPSERT` statement will be
  executed. If there is a match, the *update* / *replace* part will be carried out:

      UPSERT { page: 'index.html' }                 /* search example */
        INSERT { page: 'index.html', pageViews: 1 } /* insert part */
        UPDATE { pageViews: OLD.pageViews + 1 }     /* update part */
        IN pageViews

  `UPSERT` can be used with an `UPDATE` or `REPLACE` clause. The `UPDATE` clause will perform
  a partial update of the found document, whereas the `REPLACE` clause will replace the found
  document entirely. The `UPDATE` or `REPLACE` parts can refer to the pseudo-value `OLD`, which
  contains all attributes of the found document.

  `UPSERT` statements can optionally return values. In the following query, the return
  attribute `found` will return the found document before the `UPDATE` was applied. If no
  document was found, `found` will contain a value of `null`. The `updated` result attribute will
  contain the inserted / updated document:

      UPSERT { page: 'index.html' }                 /* search example */
        INSERT { page: 'index.html', pageViews: 1 } /* insert part */
        UPDATE { pageViews: OLD.pageViews + 1 }     /* update part */
        IN pageViews
        RETURN { found: OLD, updated: NEW }

  A more detailed description of `UPSERT` can be found here:
  http://jsteemann.github.io/blog/2015/03/27/preview-of-the-upsert-command/

* adjusted default configuration value for `--server.backlog-size` from 10 to 64.

* issue #1231: bug xor feature in AQL: LENGTH(null) == 4

  This changes the behavior of the AQL `LENGTH` function as follows:

  - if the single argument to `LENGTH()` is `null`, then the result will now be `0`. In previous
    versions of ArangoDB, the result of `LENGTH(null)` was `4`.

  - if the single argument to `LENGTH()` is `true`, then the result will now be `1`. In previous
    versions of ArangoDB, the result of `LENGTH(true)` was `4`.

  - if the single argument to `LENGTH()` is `false`, then the result will now be `0`. In previous
    versions of ArangoDB, the result of `LENGTH(false)` was `5`.

  The results of `LENGTH()` with string, numeric, array object argument values do not change.

* issue #1298: Bulk import if data already exists (#1298)

  This change extends the HTTP REST API for bulk imports as follows:

  When documents are imported and the `_key` attribute is specified for them, the import can be
  used for inserting and updating/replacing documents. Previously, the import could be used for
  inserting new documents only, and re-inserting a document with an existing key would have failed
  with a *unique key constraint violated* error.

  The above behavior is still the default. However, the API now allows controlling the behavior
  in case of a unique key constraint error via the optional URL parameter `onDuplicate`.

  This parameter can have one of the following values:

  - `error`: when a unique key constraint error occurs, do not import or update the document but
    report an error. This is the default.

  - `update`: when a unique key constraint error occurs, try to (partially) update the existing
    document with the data specified in the import. This may still fail if the document would
    violate secondary unique indexes. Only the attributes present in the import data will be
    updated and other attributes already present will be preserved. The number of updated documents
    will be reported in the `updated` attribute of the HTTP API result.

  - `replace`: when a unique key constraint error occurs, try to fully replace the existing
    document with the data specified in the import. This may still fail if the document would
    violate secondary unique indexes. The number of replaced documents will be reported in the
    `updated` attribute of the HTTP API result.

  - `ignore`: when a unique key constraint error occurs, ignore this error. There will be no
    insert, update or replace for the particular document. Ignored documents will be reported
    separately in the `ignored` attribute of the HTTP API result.

  The result of the HTTP import API will now contain the attributes `ignored` and `updated`, which
  contain the number of ignored and updated documents respectively. These attributes will contain a
  value of zero unless the `onDuplicate` URL parameter is set to either `update` or `replace`
  (in this case the `updated` attribute may contain non-zero values) or `ignore` (in this case the
  `ignored` attribute may contain a non-zero value).

  To support the feature, arangoimp also has a new command line option `--on-duplicate` which can
  have one of the values `error`, `update`, `replace`, `ignore`. The default value is `error`.

  A few examples for using arangoimp with the `--on-duplicate` option can be found here:
  http://jsteemann.github.io/blog/2015/04/14/updating-documents-with-arangoimp/

* changed behavior of `db._query()` in the ArangoShell:

  if the command's result is printed in the shell, the first 10 results will be printed. Previously
  only a basic description of the underlying query result cursor was printed. Additionally, if the
  cursor result contains more than 10 results, the cursor is assigned to a global variable `more`,
  which can be used to iterate over the cursor result.

  Example:

      arangosh [_system]> db._query("FOR i IN 1..15 RETURN i")
      [object ArangoQueryCursor, count: 15, hasMore: true]

      [
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10
      ]

      type 'more' to show more documents


      arangosh [_system]> more
      [object ArangoQueryCursor, count: 15, hasMore: false]

      [
        11,
        12,
        13,
        14,
        15
      ]

* Disallow batchSize value 0 in HTTP `POST /_api/cursor`:

  The HTTP REST API `POST /_api/cursor` does not accept a `batchSize` parameter value of
  `0` any longer. A batch size of 0 never made much sense, but previous versions of ArangoDB
  did not check for this value. Now creating a cursor using a `batchSize` value 0 will
  result in an HTTP 400 error response

* REST Server: fix memory leaks when failing to add jobs

* 'EDGES' AQL Function

  The AQL function `EDGES` got a new fifth option parameter.
  Right now only one option is available: 'includeVertices'. This is a boolean parameter
  that allows to modify the result of the `EDGES` function.
  Default is 'includeVertices: false' which does not have any effect.
  'includeVertices: true' modifies the result, such that
  {vertex: <vertexDocument>, edge: <edgeDocument>} is returned.

* INCOMPATIBLE CHANGE:

  The result format of the AQL function `NEIGHBORS` has been changed.
  Before it has returned an array of objects containing 'vertex' and 'edge'.
  Now it will only contain the vertex directly.
  Also an additional option 'includeData' has been added.
  This is used to define if only the 'vertex._id' value should be returned (false, default),
  or if the vertex should be looked up in the collection and the complete JSON should be returned
  (true).
  Using only the id values can lead to significantly improved performance if this is the only information
  required.

  In order to get the old result format prior to ArangoDB 2.6, please use the function EDGES instead.
  Edges allows for a new option 'includeVertices' which, set to true, returns exactly the format of NEIGHBORS.
  Example:

      NEIGHBORS(<vertexCollection>, <edgeCollection>, <vertex>, <direction>, <example>)

  This can now be achieved by:

      EDGES(<edgeCollection>, <vertex>, <direction>, <example>, {includeVertices: true})

  If you are nesting several NEIGHBORS steps you can speed up their performance in the following way:

  Old Example:

  FOR va IN NEIGHBORS(Users, relations, 'Users/123', 'outbound') FOR vc IN NEIGHBORS(Products, relations, va.vertex._id, 'outbound') RETURN vc

  This can now be achieved by:

  FOR va IN NEIGHBORS(Users, relations, 'Users/123', 'outbound') FOR vc IN NEIGHBORS(Products, relations, va, 'outbound', null, {includeData: true}) RETURN vc
                                                                                                          ^^^^                  ^^^^^^^^^^^^^^^^^^^
                                                                                                  Use intermediate directly     include Data for final

* INCOMPATIBLE CHANGE:

  The AQL function `GRAPH_NEIGHBORS` now provides an additional option `includeData`.
  This option allows controlling whether the function should return the complete vertices
  or just their IDs. Returning only the IDs instead of the full vertices can lead to
  improved performance .

  If provided, `includeData` is set to `true`, all vertices in the result will be returned
  with all their attributes. The default value of `includeData` is `false`.
  This makes the default function results incompatible with previous versions of ArangoDB.

  To get the old result style in ArangoDB 2.6, please set the options as follows in calls
  to `GRAPH_NEIGHBORS`:

      GRAPH_NEIGHBORS(<graph>, <vertex>, { includeData: true })

* INCOMPATIBLE CHANGE:

  The AQL function `GRAPH_COMMON_NEIGHBORS` now provides an additional option `includeData`.
  This option allows controlling whether the function should return the complete vertices
  or just their IDs. Returning only the IDs instead of the full vertices can lead to
  improved performance .

  If provided, `includeData` is set to `true`, all vertices in the result will be returned
  with all their attributes. The default value of `includeData` is `false`.
  This makes the default function results incompatible with previous versions of ArangoDB.

  To get the old result style in ArangoDB 2.6, please set the options as follows in calls
  to `GRAPH_COMMON_NEIGHBORS`:

      GRAPH_COMMON_NEIGHBORS(<graph>, <vertexExamples1>, <vertexExamples2>, { includeData: true }, { includeData: true })

* INCOMPATIBLE CHANGE:

  The AQL function `GRAPH_SHORTEST_PATH` now provides an additional option `includeData`.
  This option allows controlling whether the function should return the complete vertices
  and edges or just their IDs. Returning only the IDs instead of full vertices and edges
  can lead to improved performance .

  If provided, `includeData` is set to `true`, all vertices and edges in the result will
  be returned with all their attributes. There is also an optional parameter `includePath` of
  type object.
  It has two optional sub-attributes `vertices` and `edges`, both of type boolean.
  Both can be set individually and the result will include all vertices on the path if
  `includePath.vertices == true` and all edges if `includePath.edges == true` respectively.

  The default value of `includeData` is `false`, and paths are now excluded by default.
  This makes the default function results incompatible with previous versions of ArangoDB.

  To get the old result style in ArangoDB 2.6, please set the options as follows in calls
  to `GRAPH_SHORTEST_PATH`:

      GRAPH_SHORTEST_PATH(<graph>, <source>, <target>, { includeData: true, includePath: { edges: true, vertices: true } })

  The attributes `startVertex` and `vertex` that were present in the results of `GRAPH_SHORTEST_PATH`
  in previous versions of ArangoDB will not be produced in 2.6. To calculate these attributes in 2.6,
  please extract the first and last elements from the `vertices` result attribute.

* INCOMPATIBLE CHANGE:

  The AQL function `GRAPH_DISTANCE_TO` will now return only the id the destination vertex
  in the `vertex` attribute, and not the full vertex data with all vertex attributes.

* INCOMPATIBLE CHANGE:

  All graph measurements functions in JavaScript module `general-graph` that calculated a
  single figure previously returned an array containing just the figure. Now these functions
  will return the figure directly and not put it inside an array.

  The affected functions are:

  * `graph._absoluteEccentricity`
  * `graph._eccentricity`
  * `graph._absoluteCloseness`
  * `graph._closeness`
  * `graph._absoluteBetweenness`
  * `graph._betweenness`
  * `graph._radius`
  * `graph._diameter`

* Create the `_graphs` collection in new databases with `waitForSync` attribute set to `false`

  The previous `waitForSync` value was `true`, so default the behavior when creating and dropping
  graphs via the HTTP REST API changes as follows if the new settings are in effect:

  * `POST /_api/graph` by default returns `HTTP 202` instead of `HTTP 201`
  * `DELETE /_api/graph/graph-name` by default returns `HTTP 202` instead of `HTTP 201`

  If the `_graphs` collection still has its `waitForSync` value set to `true`, then the HTTP status
  code will not change.

* Upgraded ICU to version 54; this increases performance in many places.
  based on https://code.google.com/p/chromium/issues/detail?id=428145

* added support for HTTP push aka chunked encoding

* issue #1051: add info whether server is running in service or user mode?

  This will add a "mode" attribute to the result of the result of HTTP GET `/_api/version?details=true`

  "mode" can have the following values:

  - `standalone`: server was started manually (e.g. on command-line)
  - `service`: service is running as Windows service, in daemon mode or under the supervisor

* improve system error messages in Windows port

* increased default value of `--server.request-timeout` from 300 to 1200 seconds for client tools
  (arangosh, arangoimp, arangodump, arangorestore)

* increased default value of `--server.connect-timeout` from 3 to 5 seconds for client tools
  (arangosh, arangoimp, arangodump, arangorestore)

* added startup option `--server.foxx-queues-poll-interval`

  This startup option controls the frequency with which the Foxx queues manager is checking
  the queue (or queues) for jobs to be executed.

  The default value is `1` second. Lowering this value will result in the queue manager waking
  up and checking the queues more frequently, which may increase CPU usage of the server.
  When not using Foxx queues, this value can be raised to save some CPU time.

* added startup option `--server.foxx-queues`

  This startup option controls whether the Foxx queue manager will check queue and job entries.
  Disabling this option can reduce server load but will prevent jobs added to Foxx queues from
  being processed at all.

  The default value is `true`, enabling the Foxx queues feature.

* make Foxx queues really database-specific.

  Foxx queues were and are stored in a database-specific collection `_queues`. However, a global
  cache variable for the queues led to the queue names being treated database-independently, which
  was wrong.

  Since 2.6, Foxx queues names are truly database-specific, so the same queue name can be used in
  two different databases for two different queues. Until then, it is advisable to think of queues
  as already being database-specific, and using the database name as a queue name prefix to be
  avoid name conflicts, e.g.:

      var queueName = "myQueue";
      var Foxx = require("org/arangodb/foxx");
      Foxx.queues.create(db._name() + ":" + queueName);

* added support for Foxx queue job types defined as app scripts.

  The old job types introduced in 2.4 are still supported but are known to cause issues in 2.5
  and later when the server is restarted or the job types are not defined in every thread.

  The new job types avoid this issue by storing an explicit mount path and script name rather
  than an assuming the job type is defined globally. It is strongly recommended to convert your
  job types to the new script-based system.

* renamed Foxx sessions option "sessionStorageApp" to "sessionStorage". The option now also accepts session storages directly.

* Added the following JavaScript methods for file access:
  * fs.copyFile() to copy single files
  * fs.copyRecursive() to copy directory trees
  * fs.chmod() to set the file permissions (non-Windows only)

* Added process.env for accessing the process environment from JavaScript code

* Cluster: kickstarter shutdown routines will more precisely follow the shutdown of its nodes.

* Cluster: don't delete agency connection objects that are currently in use.

* Cluster: improve passing along of HTTP errors

* fixed issue #1247: debian init script problems

* multi-threaded index creation on collection load

  When a collection contains more than one secondary index, they can be built in memory in
  parallel when the collection is loaded. How many threads are used for parallel index creation
  is determined by the new configuration parameter `--database.index-threads`. If this is set
  to 0, indexes are built by the opening thread only and sequentially. This is equivalent to
  the behavior in 2.5 and before.

* speed up building up primary index when loading collections

* added `count` attribute to `parameters.json` files of collections. This attribute indicates
  the number of live documents in the collection on unload. It is read when the collection is
  (re)loaded to determine the initial size for the collection's primary index

* removed remainders of MRuby integration, removed arangoirb

* simplified `controllers` property in Foxx manifests. You can now specify a filename directly
  if you only want to use a single file mounted at the base URL of your Foxx app.

* simplified `exports` property in Foxx manifests. You can now specify a filename directly if
  you only want to export variables from a single file in your Foxx app.

* added support for node.js-style exports in Foxx exports. Your Foxx exports file can now export
  arbitrary values using the `module.exports` property instead of adding properties to the
  `exports` object.

* added `scripts` property to Foxx manifests. You should now specify the `setup` and `teardown`
  files as properties of the `scripts` object in your manifests and can define custom,
  app-specific scripts that can be executed from the web interface or the CLI.

* added `tests` property to Foxx manifests. You can now define test cases using the `mocha`
  framework which can then be executed inside ArangoDB.

* updated `joi` package to 6.0.8.

* added `extendible` package.

* added Foxx model lifecycle events to repositories. See #1257.

* speed up resizing of edge index.

* allow to split an edge index into buckets which are resized individually.
  This is controlled by the `indexBuckets` attribute in the `properties`
  of the collection.

* fix a cluster deadlock bug in larger clusters by marking a thread waiting
  for a lock on a DBserver as blocked


v2.5.7 (2015-08-02)
-------------------

* V8: Upgrade to version 4.1.0.27 - this is intended to be the stable V8 version.


v2.5.6 (2015-07-21)
-------------------

* alter Windows build infrastructure so we can properly store pdb files.

* potentially fixed issue #1313: Wrong metric calculation at dashboard

  Escape whitespace in process name when scanning /proc/pid/stats

  This fixes statistics values read from that file

* Fixed variable naming in AQL `COLLECT INTO` results in case the COLLECT is placed
  in a subquery which itself is followed by other constructs that require variables


v2.5.5 (2015-05-29)
-------------------

* fixed vulnerability in JWT implementation.

* fixed format string for reading /proc/pid/stat

* take into account barriers used in different V8 contexts


v2.5.4 (2015-05-14)
-------------------

* added startup option `--log.performance`: specifying this option at startup will log
  performance-related info messages, mainly timings via the regular logging mechanisms

* cluster fixes

* fix for recursive copy under Windows


v2.5.3 (2015-04-29)
-------------------

* Fix fs.move to work across filesystem borders; Fixes Foxx app installation problems;
  issue #1292.

* Fix Foxx app install when installed on a different drive on Windows

* issue #1322: strange AQL result

* issue #1318: Inconsistent db._create() syntax

* issue #1315: queries to a collection fail with an empty response if the
  collection contains specific JSON data

* issue #1300: Make arangodump not fail if target directory exists but is empty

* allow specifying higher values than SOMAXCONN for `--server.backlog-size`

  Previously, arangod would not start when a `--server.backlog-size` value was
  specified that was higher than the platform's SOMAXCONN header value.

  Now, arangod will use the user-provided value for `--server.backlog-size` and
  pass it to the listen system call even if the value is higher than SOMAXCONN.
  If the user-provided value is higher than SOMAXCONN, arangod will log a warning
  on startup.

* Fixed a cluster deadlock bug. Mark a thread that is in a RemoteBlock as
  blocked to allow for additional dispatcher threads to be started.

* Fix locking in cluster by using another ReadWriteLock class for collections.

* Add a second DispatcherQueue for AQL in the cluster. This fixes a
  cluster-AQL thread explosion bug.


v2.5.2 (2015-04-11)
-------------------

* modules stored in _modules are automatically flushed when changed

* added missing query-id parameter in documentation of HTTP DELETE `/_api/query` endpoint

* added iterator for edge index in AQL queries

  this change may lead to less edges being read when used together with a LIMIT clause

* make graph viewer in web interface issue less expensive queries for determining
  a random vertex from the graph, and for determining vertex attributes

* issue #1285: syntax error, unexpected $undefined near '@_to RETURN obj

  this allows AQL bind parameter names to also start with underscores

* moved /_api/query to C++

* issue #1289: Foxx models created from database documents expose an internal method

* added `Foxx.Repository#exists`

* parallelize initialization of V8 context in multiple threads

* fixed a possible crash when the debug-level was TRACE

* cluster: do not initialize statistics collection on each
  coordinator, this fixes a race condition at startup

* cluster: fix a startup race w.r.t. the _configuration collection

* search for db:// JavaScript modules only after all local files have been
  considered, this speeds up the require command in a cluster considerably

* general cluster speedup in certain areas


v2.5.1 (2015-03-19)
-------------------

* fixed bug that caused undefined behavior when an AQL query was killed inside
  a calculation block

* fixed memleaks in AQL query cleanup in case out-of-memory errors are thrown

* by default, Debian and RedHat packages are built with debug symbols

* added option `--database.ignore-logfile-errors`

  This option controls how collection datafiles with a CRC mismatch are treated.

  If set to `false`, CRC mismatch errors in collection datafiles will lead
  to a collection not being loaded at all. If a collection needs to be loaded
  during WAL recovery, the WAL recovery will also abort (if not forced with
  `--wal.ignore-recovery-errors true`). Setting this flag to `false` protects
  users from unintentionally using a collection with corrupted datafiles, from
  which only a subset of the original data can be recovered.

  If set to `true`, CRC mismatch errors in collection datafiles will lead to
  the datafile being partially loaded. All data up to until the mismatch will
  be loaded. This will enable users to continue with collection datafiles
  that are corrupted, but will result in only a partial load of the data.
  The WAL recovery will still abort when encountering a collection with a
  corrupted datafile, at least if `--wal.ignore-recovery-errors` is not set to
  `true`.

  The default value is *true*, so for collections with corrupted datafiles
  there might be partial data loads once the WAL recovery has finished. If
  the WAL recovery will need to load a collection with a corrupted datafile,
  it will still stop when using the default values.

* INCOMPATIBLE CHANGE:

  make the arangod server refuse to start if during startup it finds a non-readable
  `parameter.json` file for a database or a collection.

  Stopping the startup process in this case requires manual intervention (fixing
  the unreadable files), but prevents follow-up errors due to ignored databases or
  collections from happening.

* datafiles and `parameter.json` files written by arangod are now created with read and write
  privileges for the arangod process user, and with read and write privileges for the arangod
  process group.

  Previously, these files were created with user read and write permissions only.

* INCOMPATIBLE CHANGE:

  abort WAL recovery if one of the collection's datafiles cannot be opened

* INCOMPATIBLE CHANGE:

  never try to raise the privileges after dropping them, this can lead to a race condition while
  running the recovery

  If you require to run ArangoDB on a port lower than 1024, you must run ArangoDB as root.

* fixed inefficiencies in `remove` methods of general-graph module

* added option `--database.slow-query-threshold` for controlling the default AQL slow query
  threshold value on server start

* add system error strings for Windows on many places

* rework service startup so we announce 'RUNNING' only when we're finished starting.

* use the Windows eventlog for FATAL and ERROR - log messages

* fix service handling in NSIS Windows installer, specify human readable name

* add the ICU_DATA environment variable to the fatal error messages

* fixed issue #1265: arangod crashed with SIGSEGV

* fixed issue #1241: Wildcards in examples


v2.5.0 (2015-03-09)
-------------------

* installer fixes for Windows

* fix for downloading Foxx

* fixed issue #1258: http pipelining not working?


v2.5.0-beta4 (2015-03-05)
-------------------------

* fixed issue #1247: debian init script problems


v2.5.0-beta3 (2015-02-27)
-------------------------

* fix Windows install path calculation in arango

* fix Windows logging of long strings

* fix possible undefinedness of const strings in Windows


v2.5.0-beta2 (2015-02-23)
-------------------------

* fixed issue #1256: agency binary not found #1256

* fixed issue #1230: API: document/col-name/_key and cursor return different floats

* front-end: dashboard tries not to (re)load statistics if user has no access

* V8: Upgrade to version 3.31.74.1

* etcd: Upgrade to version 2.0 - This requires go 1.3 to compile at least.

* refuse to startup if ICU wasn't initialized, this will i.e. prevent errors from being printed,
  and libraries from being loaded.

* front-end: unwanted removal of index table header after creating new index

* fixed issue #1248: chrome: applications filtering not working

* fixed issue #1198: queries remain in aql editor (front-end) if you navigate through different tabs

* Simplify usage of Foxx

  Thanks to our user feedback we learned that Foxx is a powerful, yet rather complicated concept.
  With this release we tried to make it less complicated while keeping all its strength.
  That includes a rewrite of the documentation as well as some code changes as listed below:

  * Moved Foxx applications to a different folder.

    The naming convention now is: <app-path>/_db/<dbname>/<mountpoint>/APP
    Before it was: <app-path>/databases/<dbname>/<appname>:<appversion>
    This caused some trouble as apps where cached based on name and version and updates did not apply.
    Hence the path on filesystem and the app's access URL had no relation to one another.
    Now the path on filesystem is identical to the URL (except for slashes and the appended APP)

  * Rewrite of Foxx routing

    The routing of Foxx has been exposed to major internal changes we adjusted because of user feedback.
    This allows us to set the development mode per mountpoint without having to change paths and hold
    apps at separate locations.

  * Foxx Development mode

    The development mode used until 2.4 is gone. It has been replaced by a much more mature version.
    This includes the deprecation of the javascript.dev-app-path parameter, which is useless since 2.5.
    Instead of having two separate app directories for production and development, apps now reside in
    one place, which is used for production as well as for development.
    Apps can still be put into development mode, changing their behavior compared to production mode.
    Development mode apps are still reread from disk at every request, and still they ship more debug
    output.

    This change has also made the startup options `--javascript.frontend-development-mode` and
    `--javascript.dev-app-path` obsolete. The former option will not have any effect when set, and the
    latter option is only read and used during the upgrade to 2.5 and does not have any effects later.

  * Foxx install process

    Installing Foxx apps has been a two step process: import them into ArangoDB and mount them at a
    specific mountpoint. These operations have been joined together. You can install an app at one
    mountpoint, that's it. No fetch, mount, unmount, purge cycle anymore. The commands have been
    simplified to just:

    * install: get your Foxx app up and running
    * uninstall: shut it down and erase it from disk

  * Foxx error output

    Until 2.4 the errors produced by Foxx were not optimal. Often, the error message was just
    `unable to parse manifest` and contained only an internal stack trace.
    In 2.5 we made major improvements there, including a much more fine-grained error output that
    helps you debug your Foxx apps. The error message printed is now much closer to its source and
    should help you track it down.

    Also we added the default handlers for unhandled errors in Foxx apps:

    * You will get a nice internal error page whenever your Foxx app is called but was not installed
      due to any error
    * You will get a proper error message when having an uncaught error appears in any app route

    In production mode the messages above will NOT contain any information about your Foxx internals
    and are safe to be exposed to third party users.
    In development mode the messages above will contain the stacktrace (if available), making it easier for
    your in-house devs to track down errors in the application.

* added `console` object to Foxx apps. All Foxx apps now have a console object implementing
  the familiar Console API in their global scope, which can be used to log diagnostic
  messages to the database.

* added `org/arangodb/request` module, which provides a simple API for making HTTP requests
  to external services.

* added optimizer rule `propagate-constant-attributes`

  This rule will look inside `FILTER` conditions for constant value equality comparisons,
  and insert the constant values in other places in `FILTER`s. For example, the rule will
  insert `42` instead of `i.value` in the second `FILTER` of the following query:

      FOR i IN c1 FOR j IN c2 FILTER i.value == 42 FILTER j.value == i.value RETURN 1

* added `filtered` value to AQL query execution statistics

  This value indicates how many documents were filtered by `FilterNode`s in the AQL query.
  Note that `IndexRangeNode`s can also filter documents by selecting only the required ranges
  from the index. The `filtered` value will not include the work done by `IndexRangeNode`s,
  but only the work performed by `FilterNode`s.

* added support for sparse hash and skiplist indexes

  Hash and skiplist indexes can optionally be made sparse. Sparse indexes exclude documents
  in which at least one of the index attributes is either not set or has a value of `null`.

  As such documents are excluded from sparse indexes, they may contain fewer documents than
  their non-sparse counterparts. This enables faster indexing and can lead to reduced memory
  usage in case the indexed attribute does occur only in some, but not all documents of the
  collection. Sparse indexes will also reduce the number of collisions in non-unique hash
  indexes in case non-existing or optional attributes are indexed.

  In order to create a sparse index, an object with the attribute `sparse` can be added to
  the index creation commands:

      db.collection.ensureHashIndex(attributeName, { sparse: true });
      db.collection.ensureHashIndex(attributeName1, attributeName2, { sparse: true });
      db.collection.ensureUniqueConstraint(attributeName, { sparse: true });
      db.collection.ensureUniqueConstraint(attributeName1, attributeName2, { sparse: true });

      db.collection.ensureSkiplist(attributeName, { sparse: true });
      db.collection.ensureSkiplist(attributeName1, attributeName2, { sparse: true });
      db.collection.ensureUniqueSkiplist(attributeName, { sparse: true });
      db.collection.ensureUniqueSkiplist(attributeName1, attributeName2, { sparse: true });

  Note that in place of the above specialized index creation commands, it is recommended to use
  the more general index creation command `ensureIndex`:

  ```js
  db.collection.ensureIndex({ type: "hash", sparse: true, unique: true, fields: [ attributeName ] });
  db.collection.ensureIndex({ type: "skiplist", sparse: false, unique: false, fields: [ "a", "b" ] });
  ```

  When not explicitly set, the `sparse` attribute defaults to `false` for new indexes.

  This causes a change in behavior when creating a unique hash index without specifying the
  sparse flag: in 2.4, unique hash indexes were implicitly sparse, always excluding `null` values.
  There was no option to control this behavior, and sparsity was neither supported for non-unique
  hash indexes nor skiplists in 2.4. This implicit sparsity of unique hash indexes was considered
  an inconsistency, and therefore the behavior was cleaned up in 2.5. As of 2.5, indexes will
  only be created sparse if sparsity is explicitly requested. Existing unique hash indexes from 2.4
  or before will automatically be migrated so they are still sparse after the upgrade to 2.5.

  Geo indexes are implicitly sparse, meaning documents without the indexed location attribute or
  containing invalid location coordinate values will be excluded from the index automatically. This
  is also a change when compared to pre-2.5 behavior, when documents with missing or invalid
  coordinate values may have caused errors on insertion when the geo index' `unique` flag was set
  and its `ignoreNull` flag was not.

  This was confusing and has been rectified in 2.5. The method `ensureGeoConstaint()` now does the
  same as `ensureGeoIndex()`. Furthermore, the attributes `constraint`, `unique`, `ignoreNull` and
  `sparse` flags are now completely ignored when creating geo indexes.

  The same is true for fulltext indexes. There is no need to specify non-uniqueness or sparsity for
  geo or fulltext indexes. They will always be non-unique and sparse.

  As sparse indexes may exclude some documents, they cannot be used for every type of query.
  Sparse hash indexes cannot be used to find documents for which at least one of the indexed
  attributes has a value of `null`. For example, the following AQL query cannot use a sparse
  index, even if one was created on attribute `attr`:

      FOR doc In collection
        FILTER doc.attr == null
        RETURN doc

  If the lookup value is non-constant, a sparse index may or may not be used, depending on
  the other types of conditions in the query. If the optimizer can safely determine that
  the lookup value cannot be `null`, a sparse index may be used. When uncertain, the optimizer
  will not make use of a sparse index in a query in order to produce correct results.

  For example, the following queries cannot use a sparse index on `attr` because the optimizer
  will not know beforehand whether the comparison values for `doc.attr` will include `null`:

      FOR doc In collection
        FILTER doc.attr == SOME_FUNCTION(...)
        RETURN doc

      FOR other IN otherCollection
        FOR doc In collection
          FILTER doc.attr == other.attr
          RETURN doc

  Sparse skiplist indexes can be used for sorting if the optimizer can safely detect that the
  index range does not include `null` for any of the index attributes.

* inspection of AQL data-modification queries will now detect if the data-modification part
  of the query can run in lockstep with the data retrieval part of the query, or if the data
  retrieval part must be executed before the data modification can start.

  Executing the two in lockstep allows using much smaller buffers for intermediate results
  and starts the actual data-modification operations much earlier than if the two phases
  were executed separately.

* Allow dynamic attribute names in AQL object literals

  This allows using arbitrary expressions to construct attribute names in object
  literals specified in AQL queries. To disambiguate expressions and other unquoted
  attribute names, dynamic attribute names need to be enclosed in brackets (`[` and `]`).
  Example:

      FOR i IN 1..100
        RETURN { [ CONCAT('value-of-', i) ] : i }

* make AQL optimizer rule "use-index-for-sort" remove sort also in case a non-sorted
  index (e.g. a hash index) is used for only equality lookups and all sort attributes
  are covered by the index.

  Example that does not require an extra sort (needs hash index on `value`):

      FOR doc IN collection FILTER doc.value == 1 SORT doc.value RETURN doc

  Another example that does not require an extra sort (with hash index on `value1`, `value2`):

      FOR doc IN collection FILTER doc.value1 == 1 && doc.value2 == 2 SORT doc.value1, doc.value2 RETURN doc

* make AQL optimizer rule "use-index-for-sort" remove sort also in case the sort criteria
  excludes the left-most index attributes, but the left-most index attributes are used
  by the index for equality-only lookups.

  Example that can use the index for sorting (needs skiplist index on `value1`, `value2`):

      FOR doc IN collection FILTER doc.value1 == 1 SORT doc.value2 RETURN doc

* added selectivity estimates for primary index, edge index, and hash index

  The selectivity estimates are returned by the `GET /_api/index` REST API method
  in a sub-attribute `selectivityEstimate` for each index that supports it. This
  attribute will be omitted for indexes that do not provide selectivity estimates.
  If provided, the selectivity estimate will be a numeric value between 0 and 1.

  Selectivity estimates will also be reported in the result of `collection.getIndexes()`
  for all indexes that support this. If no selectivity estimate can be determined for
  an index, the attribute `selectivityEstimate` will be omitted here, too.

  The web interface also shows selectivity estimates for each index that supports this.

  Currently the following index types can provide selectivity estimates:
  - primary index
  - edge index
  - hash index (unique and non-unique)

  No selectivity estimates will be provided when running in cluster mode.

* fixed issue #1226: arangod log issues

* added additional logger if arangod is started in foreground mode on a tty

* added AQL optimizer rule "move-calculations-down"

* use exclusive native SRWLocks on Windows instead of native mutexes

* added AQL functions `MD5`, `SHA1`, and `RANDOM_TOKEN`.

* reduced number of string allocations when parsing certain AQL queries

  parsing numbers (integers or doubles) does not require a string allocation
  per number anymore

* RequestContext#bodyParam now accepts arbitrary joi schemas and rejects invalid (but well-formed) request bodies.

* enforce that AQL user functions are wrapped inside JavaScript function () declarations

  AQL user functions were always expected to be wrapped inside a JavaScript function, but previously
  this was not enforced when registering a user function. Enforcing the AQL user functions to be contained
  inside functions prevents functions from doing some unexpected things that may have led to undefined
  behavior.

* Windows service uninstalling: only remove service if it points to the currently running binary,
  or --force was specified.

* Windows (debug only): print stacktraces on crash and run minidump

* Windows (cygwin): if you run arangosh in a cygwin shell or via ssh we will detect this and use
  the appropriate output functions.

* Windows: improve process management

* fix IPv6 reverse ip lookups - so far we only did IPv4 addresses.

* improve join documentation, add outer join example

* run jslint for unit tests too, to prevent "memory leaks" by global js objects with native code.

* fix error logging for exceptions - we wouldn't log the exception message itself so far.

* improve error reporting in the http client (Windows & *nix)

* improve error reports in cluster

* Standard errors can now contain custom messages.


v2.4.7 (XXXX-XX-XX)
-------------------

* fixed issue #1282: Geo WITHIN_RECTANGLE for nested lat/lng


v2.4.6 (2015-03-18)
-------------------

* added option `--database.ignore-logfile-errors`

  This option controls how collection datafiles with a CRC mismatch are treated.

  If set to `false`, CRC mismatch errors in collection datafiles will lead
  to a collection not being loaded at all. If a collection needs to be loaded
  during WAL recovery, the WAL recovery will also abort (if not forced with
  `--wal.ignore-recovery-errors true`). Setting this flag to `false` protects
  users from unintentionally using a collection with corrupted datafiles, from
  which only a subset of the original data can be recovered.

  If set to `true`, CRC mismatch errors in collection datafiles will lead to
  the datafile being partially loaded. All data up to until the mismatch will
  be loaded. This will enable users to continue with a collection datafiles
  that are corrupted, but will result in only a partial load of the data.
  The WAL recovery will still abort when encountering a collection with a
  corrupted datafile, at least if `--wal.ignore-recovery-errors` is not set to
  `true`.

  The default value is *true*, so for collections with corrupted datafiles
  there might be partial data loads once the WAL recovery has finished. If
  the WAL recovery will need to load a collection with a corrupted datafile,
  it will still stop when using the default values.

* INCOMPATIBLE CHANGE:

  make the arangod server refuse to start if during startup it finds a non-readable
  `parameter.json` file for a database or a collection.

  Stopping the startup process in this case requires manual intervention (fixing
  the unreadable files), but prevents follow-up errors due to ignored databases or
  collections from happening.

* datafiles and `parameter.json` files written by arangod are now created with read and write
  privileges for the arangod process user, and with read and write privileges for the arangod
  process group.

  Previously, these files were created with user read and write permissions only.

* INCOMPATIBLE CHANGE:

  abort WAL recovery if one of the collection's datafiles cannot be opened

* INCOMPATIBLE CHANGE:

  never try to raise the privileges after dropping them, this can lead to a race condition while
  running the recovery

  If you require to run ArangoDB on a port lower than 1024, you must run ArangoDB as root.

* fixed inefficiencies in `remove` methods of general-graph module

* added option `--database.slow-query-threshold` for controlling the default AQL slow query
  threshold value on server start


v2.4.5 (2015-03-16)
-------------------

* added elapsed time to HTTP request logging output (`--log.requests-file`)

* added AQL current and slow query tracking, killing of AQL queries

  This change enables retrieving the list of currently running AQL queries inside the selected database.
  AQL queries with an execution time beyond a certain threshold can be moved to a "slow query" facility
  and retrieved from there. Queries can also be killed by specifying the query id.

  This change adds the following HTTP REST APIs:

  - `GET /_api/query/current`: for retrieving the list of currently running queries
  - `GET /_api/query/slow`: for retrieving the list of slow queries
  - `DELETE /_api/query/slow`: for clearing the list of slow queries
  - `GET /_api/query/properties`: for retrieving the properties for query tracking
  - `PUT /_api/query/properties`: for adjusting the properties for query tracking
  - `DELETE /_api/query/<id>`: for killing an AQL query

  The following JavaScript APIs have been added:

  - require("org/arangodb/aql/queries").current();
  - require("org/arangodb/aql/queries").slow();
  - require("org/arangodb/aql/queries").clearSlow();
  - require("org/arangodb/aql/queries").properties();
  - require("org/arangodb/aql/queries").kill();

* fixed issue #1265: arangod crashed with SIGSEGV

* fixed issue #1241: Wildcards in examples

* fixed comment parsing in Foxx controllers


v2.4.4 (2015-02-24)
-------------------

* fixed the generation template for foxx apps. It now does not create deprecated functions anymore

* add custom visitor functionality for `GRAPH_NEIGHBORS` function, too

* increased default value of traversal option *maxIterations* to 100 times of its previous
  default value


v2.4.3 (2015-02-06)
-------------------

* fix multi-threading with openssl when running under Windows

* fix timeout on socket operations when running under Windows

* Fixed an error in Foxx routing which caused some apps that worked in 2.4.1 to fail with status 500: `undefined is not a function` errors in 2.4.2
  This error was occurring due to seldom internal rerouting introduced by the malformed application handler.


v2.4.2 (2015-01-30)
-------------------

* added custom visitor functionality for AQL traversals

  This allows more complex result processing in traversals triggered by AQL. A few examples
  are shown in [this article](http://jsteemann.github.io/blog/2015/01/28/using-custom-visitors-in-aql-graph-traversals/).

* improved number of results estimated for nodes of type EnumerateListNode and SubqueryNode
  in AQL explain output

* added AQL explain helper to explain arbitrary AQL queries

  The helper function prints the query execution plan and the indexes to be used in the
  query. It can be invoked from the ArangoShell or the web interface as follows:

      require("org/arangodb/aql/explainer").explain(query);

* enable use of indexes for certain AQL conditions with non-equality predicates, in
  case the condition(s) also refer to indexed attributes

  The following queries will now be able to use indexes:

      FILTER a.indexed == ... && a.indexed != ...
      FILTER a.indexed == ... && a.nonIndexed != ...
      FILTER a.indexed == ... && ! (a.indexed == ...)
      FILTER a.indexed == ... && ! (a.nonIndexed == ...)
      FILTER a.indexed == ... && ! (a.indexed != ...)
      FILTER a.indexed == ... && ! (a.nonIndexed != ...)
      FILTER (a.indexed == ... && a.nonIndexed == ...) || (a.indexed == ... && a.nonIndexed == ...)
      FILTER (a.indexed == ... && a.nonIndexed != ...) || (a.indexed == ... && a.nonIndexed != ...)

* Fixed spuriously occurring "collection not found" errors when running queries on local
  collections on a cluster DB server

* Fixed upload of Foxx applications to the server for apps exceeding approx. 1 MB zipped.

* Malformed Foxx applications will now return a more useful error when any route is requested.

  In Production a Foxx app mounted on /app will display an html page on /app/* stating a 503 Service temporarily not available.
  It will not state any information about your Application.
  Before it was a 404 Not Found without any information and not distinguishable from a correct not found on your route.

  In Development Mode the html page also contains information about the error occurred.

* Unhandled errors thrown in Foxx routes are now handled by the Foxx framework itself.

  In Production the route will return a status 500 with a body {error: "Error statement"}.
  In Development the route will return a status 500 with a body {error: "Error statement", stack: "..."}

  Before, it was status 500 with a plain text stack including ArangoDB internal routing information.

* The Applications tab in web interface will now request development apps more often.
  So if you have a fixed a syntax error in your app it should always be visible after reload.


v2.4.1 (2015-01-19)
-------------------

* improved WAL recovery output

* fixed certain OR optimizations in AQL optimizer

* better diagnostics for arangoimp

* fixed invalid result of HTTP REST API method `/_admin/foxx/rescan`

* fixed possible segmentation fault when passing a Buffer object into a V8 function
  as a parameter

* updated AQB module to 1.8.0.


v2.4.0 (2015-01-13)
-------------------

* updated AQB module to 1.7.0.

* fixed V8 integration-related crashes

* make `fs.move(src, dest)` also fail when both `src` and `dest` are
  existing directories. This ensures the same behavior of the move operation
  on different platforms.

* fixed AQL insert operation for multi-shard collections in cluster

* added optional return value for AQL data-modification queries.
  This allows returning the documents inserted, removed or updated with the query, e.g.

      FOR doc IN docs REMOVE doc._key IN docs LET removed = OLD RETURN removed
      FOR doc IN docs INSERT { } IN docs LET inserted = NEW RETURN inserted
      FOR doc IN docs UPDATE doc._key WITH { } IN docs LET previous = OLD RETURN previous
      FOR doc IN docs UPDATE doc._key WITH { } IN docs LET updated = NEW RETURN updated

  The variables `OLD` and `NEW` are automatically available when a `REMOVE`, `INSERT`,
  `UPDATE` or `REPLACE` statement is immediately followed by a `LET` statement.
  Note that the `LET` and `RETURN` statements in data-modification queries are not as
  flexible as the general versions of `LET` and `RETURN`. When returning documents from
  data-modification operations, only a single variable can be assigned using `LET`, and
  the assignment can only be either `OLD` or `NEW`, but not an arbitrary expression. The
  `RETURN` statement also allows using the just-created variable only, and no arbitrary
  expressions.


v2.4.0-beta1 (2014-12-26)
--------------------------

* fixed superstates in FoxxGenerator

* fixed issue #1065: Aardvark: added creation of documents and edges with _key property

* fixed issue #1198: Aardvark: current AQL editor query is now cached

* Upgraded V8 version from 3.16.14 to 3.29.59

  The built-in version of V8 has been upgraded from 3.16.14 to 3.29.59.
  This activates several ES6 (also dubbed *Harmony* or *ES.next*) features in
  ArangoDB, both in the ArangoShell and the ArangoDB server. They can be
  used for scripting and in server-side actions such as Foxx routes, traversals
  etc.

  The following ES6 features are available in ArangoDB 2.4 by default:

  * iterators
  * the `of` operator
  * symbols
  * predefined collections types (Map, Set etc.)
  * typed arrays

  Many other ES6 features are disabled by default, but can be made available by
  starting arangod or arangosh with the appropriate options:

  * arrow functions
  * proxies
  * generators
  * String, Array, and Number enhancements
  * constants
  * enhanced object and numeric literals

  To activate all these ES6 features in arangod or arangosh, start it with
  the following options:

      arangosh --javascript.v8-options="--harmony --harmony_generators"

  More details on the available ES6 features can be found in
  [this blog](https://jsteemann.github.io/blog/2014/12/19/using-es6-features-in-arangodb/).

* Added Foxx generator for building Hypermedia APIs

  A more detailed description is [here](https://www.arangodb.com/2014/12/08/building-hypermedia-apis-foxxgenerator)

* New `Applications` tab in web interface:

  The `applications` tab got a complete redesign.
  It will now only show applications that are currently running on ArangoDB.
  For a selected application, a new detailed view has been created.
  This view provides a better overview of the app:
  * author
  * license
  * version
  * contributors
  * download links
  * API documentation

  To install a new application, a new dialog is now available.
  It provides the features already available in the console application `foxx-manager` plus some more:
  * install an application from Github
  * install an application from a zip file
  * install an application from ArangoDB's application store
  * create a new application from scratch: this feature uses a generator to
    create a Foxx application with pre-defined CRUD methods for a given list
    of collections. The generated Foxx app can either be downloaded as a zip file or
    be installed on the server. Starting with a new Foxx app has never been easier.

* fixed issue #1102: Aardvark: Layout bug in documents overview

  The documents overview was entirely destroyed in some situations on Firefox.
  We replaced the plugin we used there.

* fixed issue #1168: Aardvark: pagination buttons jumping

* fixed issue #1161: Aardvark: Click on Import JSON imports previously uploaded file

* removed configure options `--enable-all-in-one-v8`, `--enable-all-in-one-icu`,
  and `--enable-all-in-one-libev`.

* global internal rename to fix naming incompatibilities with JSON:

  Internal functions with names containing `array` have been renamed to `object`,
  internal functions with names containing `list` have been renamed to `array`.
  The renaming was mainly done in the C++ parts. The documentation has also been
  adjusted so that the correct JSON type names are used in most places.

  The change also led to the addition of a few function aliases in AQL:

  * `TO_LIST` now is an alias of the new `TO_ARRAY`
  * `IS_LIST` now is an alias of the new `IS_ARRAY`
  * `IS_DOCUMENT` now is an alias of the new `IS_OBJECT`

  The changed also renamed the option `mergeArrays` to `mergeObjects` for AQL
  data-modification query options and HTTP document modification API

* AQL: added optimizer rule "remove-filter-covered-by-index"

  This rule removes FilterNodes and CalculationNodes from an execution plan if the
  filter is already covered by a previous IndexRangeNode. Removing the CalculationNode
  and the FilterNode will speed up query execution because the query requires less
  computation.

* AQL: added optimizer rule "remove-sort-rand"

  This rule removes a `SORT RAND()` expression from a query and moves the random
  iteration into the appropriate `EnumerateCollectionNode`. This is more efficient
  than individually enumerating and then sorting randomly.

* AQL: range optimizations for IN and OR

  This change enables usage of indexes for several additional cases. Filters containing
  the `IN` operator can now make use of indexes, and multiple OR- or AND-combined filter
  conditions can now also use indexes if the filters are accessing the same indexed
  attribute.

  Here are a few examples of queries that can now use indexes but couldn't before:

    FOR doc IN collection
      FILTER doc.indexedAttribute == 1 || doc.indexedAttribute > 99
      RETURN doc

    FOR doc IN collection
      FILTER doc.indexedAttribute IN [ 3, 42 ] || doc.indexedAttribute > 99
      RETURN doc

    FOR doc IN collection
      FILTER (doc.indexedAttribute > 2 && doc.indexedAttribute < 10) ||
             (doc.indexedAttribute > 23 && doc.indexedAttribute < 42)
      RETURN doc

* fixed issue #500: AQL parentheses issue

  This change allows passing subqueries as AQL function parameters without using
  duplicate brackets (e.g. `FUNC(query)` instead of `FUNC((query))`

* added optional `COUNT` clause to AQL `COLLECT`

  This allows more efficient group count calculation queries, e.g.

      FOR doc IN collection
        COLLECT age = doc.age WITH COUNT INTO length
        RETURN { age: age, count: length }

  A count-only query is also possible:

      FOR doc IN collection
        COLLECT WITH COUNT INTO length
        RETURN length

* fixed missing makeDirectory when fetching a Foxx application from a zip file

* fixed issue #1134: Change the default endpoint to localhost

  This change will modify the IP address ArangoDB listens on to 127.0.0.1 by default.
  This will make new ArangoDB installations unaccessible from clients other than
  localhost unless changed. This is a security feature.

  To make ArangoDB accessible from any client, change the server's configuration
  (`--server.endpoint`) to either `tcp://0.0.0.0:8529` or the server's publicly
  visible IP address.

* deprecated `Repository#modelPrototype`. Use `Repository#model` instead.

* IMPORTANT CHANGE: by default, system collections are included in replication and all
  replication API return values. This will lead to user accounts and credentials
  data being replicated from master to slave servers. This may overwrite
  slave-specific database users.

  If this is undesired, the `_users` collection can be excluded from replication
  easily by setting the `includeSystem` attribute to `false` in the following commands:

  * replication.sync({ includeSystem: false });
  * replication.applier.properties({ includeSystem: false });

  This will exclude all system collections (including `_aqlfunctions`, `_graphs` etc.)
  from the initial synchronization and the continuous replication.

  If this is also undesired, it is also possible to specify a list of collections to
  exclude from the initial synchronization and the continuous replication using the
  `restrictCollections` attribute, e.g.:

      replication.applier.properties({
        includeSystem: true,
        restrictType: "exclude",
        restrictCollections: [ "_users", "_graphs", "foo" ]
      });

  The HTTP API methods for fetching the replication inventory and for dumping collections
  also support the `includeSystem` control flag via a URL parameter.

* removed DEPRECATED replication methods:
  * `replication.logger.start()`
  * `replication.logger.stop()`
  * `replication.logger.properties()`
  * HTTP PUT `/_api/replication/logger-start`
  * HTTP PUT `/_api/replication/logger-stop`
  * HTTP GET `/_api/replication/logger-config`
  * HTTP PUT `/_api/replication/logger-config`

* fixed issue #1174, which was due to locking problems in distributed
  AQL execution

* improved cluster locking for AQL avoiding deadlocks

* use DistributeNode for modifying queries with REPLACE and UPDATE, if
  possible


v2.3.6 (2015-XX-XX)
-------------------

* fixed AQL subquery optimization that produced wrong result when multiple subqueries
  directly followed each other and and a directly following `LET` statement did refer
  to any but the first subquery.


v2.3.5 (2015-01-16)
-------------------

* fixed intermittent 404 errors in Foxx apps after mounting or unmounting apps

* fixed issue #1200: Expansion operator results in "Cannot call method 'forEach' of null"

* fixed issue #1199: Cannot unlink root node of plan


v2.3.4 (2014-12-23)
-------------------

* fixed cerberus path for MyArangoDB


v2.3.3 (2014-12-17)
-------------------

* fixed error handling in instantiation of distributed AQL queries, this
  also fixes a bug in cluster startup with many servers

* issue #1185: parse non-fractional JSON numbers with exponent (e.g. `4e-261`)

* issue #1159: allow --server.request-timeout and --server.connect-timeout of 0


v2.3.2 (2014-12-09)
-------------------

* fixed issue #1177: Fix bug in the user app's storage

* fixed issue #1173: AQL Editor "Save current query" resets user password

* fixed missing makeDirectory when fetching a Foxx application from a zip file

* put in warning about default changed: fixed issue #1134: Change the default endpoint to localhost

* fixed issue #1163: invalid fullCount value returned from AQL

* fixed range operator precedence

* limit default maximum number of plans created by AQL optimizer to 256 (from 1024)

* make AQL optimizer not generate an extra plan if an index can be used, but modify
  existing plans in place

* fixed AQL cursor ttl (time-to-live) issue

  Any user-specified cursor ttl value was not honored since 2.3.0.

* fixed segfault in AQL query hash index setup with unknown shapes

* fixed memleaks

* added AQL optimizer rule for removing `INTO` from a `COLLECT` statement if not needed

* fixed issue #1131

  This change provides the `KEEP` clause for `COLLECT ... INTO`. The `KEEP` clause
  allows controlling which variables will be kept in the variable created by `INTO`.

* fixed issue #1147, must protect dispatcher ID for etcd

v2.3.1 (2014-11-28)
-------------------

* recreate password if missing during upgrade

* fixed issue #1126

* fixed non-working subquery index optimizations

* do not restrict summary of Foxx applications to 60 characters

* fixed display of "required" path parameters in Foxx application documentation

* added more optimizations of constants values in AQL FILTER conditions

* fixed invalid or-to-in optimization for FILTERs containing comparisons
  with boolean values

* fixed replication of `_graphs` collection

* added AQL list functions `PUSH`, `POP`, `UNSHIFT`, `SHIFT`, `REMOVE_VALUES`,
  `REMOVE_VALUE`, `REMOVE_NTH` and `APPEND`

* added AQL functions `CALL` and `APPLY` to dynamically call other functions

* fixed AQL optimizer cost estimation for LIMIT node

* prevent Foxx queues from permanently writing to the journal even when
  server is idle

* fixed AQL COLLECT statement with INTO clause, which copied more variables
  than v2.2 and thus lead to too much memory consumption.
  This deals with #1107.

* fixed AQL COLLECT statement, this concerned every COLLECT statement,
  only the first group had access to the values of the variables before
  the COLLECT statement. This deals with #1127.

* fixed some AQL internals, where sometimes too many items were
  fetched from upstream in the presence of a LIMIT clause. This should
  generally improve performance.


v2.3.0 (2014-11-18)
-------------------

* fixed syslog flags. `--log.syslog` is deprecated and setting it has no effect,
  `--log.facility` now works as described. Application name has been changed from
  `triagens` to `arangod`. It can be changed using `--log.application`. The syslog
  will only contain the actual log message. The datetime prefix is omitted.

* fixed deflate in SimpleHttpClient

* fixed issue #1104: edgeExamples broken or changed

* fixed issue #1103: Error while importing user queries

* fixed issue #1100: AQL: HAS() fails on doc[attribute_name]

* fixed issue #1098: runtime error when creating graph vertex

* hide system applications in **Applications** tab by default

  Display of system applications can be toggled by using the *system applications*
  toggle in the UI.

* added HTTP REST API for managing tasks (`/_api/tasks`)

* allow passing character lists as optional parameter to AQL functions `TRIM`,
  `LTRIM` and `RTRIM`

  These functions now support trimming using custom character lists. If no character
  lists are specified, all whitespace characters will be removed as previously:

      TRIM("  foobar\t \r\n ")         // "foobar"
      TRIM(";foo;bar;baz, ", "; ")     // "foo;bar;baz"

* added AQL string functions `LTRIM`, `RTRIM`, `FIND_FIRST`, `FIND_LAST`, `SPLIT`,
  `SUBSTITUTE`

* added AQL functions `ZIP`, `VALUES` and `PERCENTILE`

* made AQL functions `CONCAT` and `CONCAT_SEPARATOR` work with list arguments

* dynamically create extra dispatcher threads if required

* fixed issue #1097: schemas in the API docs no longer show required properties as optional


v2.3.0-beta2 (2014-11-08)
-------------------------

* front-end: new icons for uploading and downloading JSON documents into a collection

* front-end: fixed documents pagination css display error

* front-end: fixed flickering of the progress view

* front-end: fixed missing event for documents filter function

* front-end: jsoneditor: added CMD+Return (Mac) CTRL+Return (Linux/Win) shortkey for
  saving a document

* front-end: added information tooltip for uploading json documents.

* front-end: added database management view to the collapsed navigation menu

* front-end: added collection truncation feature

* fixed issue #1086: arangoimp: Odd errors if arguments are not given properly

* performance improvements for AQL queries that use JavaScript-based expressions
  internally

* added AQL geo functions `WITHIN_RECTANGLE` and `IS_IN_POLYGON`

* fixed non-working query results download in AQL editor of web interface

* removed debug print message in AQL editor query export routine

* fixed issue #1075: Aardvark: user name required even if auth is off #1075

  The fix for this prefills the username input field with the current user's
  account name if any and `root` (the default username) otherwise. Additionally,
  the tooltip text has been slightly adjusted.

* fixed issue #1069: Add 'raw' link to swagger ui so that the raw swagger
  json can easily be retrieved

  This adds a link to the Swagger API docs to an application's detail view in
  the **Applications** tab of the web interface. The link produces the Swagger
  JSON directly. If authentication is turned on, the link requires authentication,
  too.

* documentation updates


v2.3.0-beta1 (2014-11-01)
-------------------------

* added dedicated `NOT IN` operator for AQL

  Previously, a `NOT IN` was only achievable by writing a negated `IN` condition:

      FOR i IN ... FILTER ! (i IN [ 23, 42 ]) ...

  This can now alternatively be expressed more intuitively as follows:

      FOR i IN ... FILTER i NOT IN [ 23, 42 ] ...

* added alternative logical operator syntax for AQL

  Previously, the logical operators in AQL could only be written as:
  - `&&`: logical and
  - `||`: logical or
  - `!`: negation

  ArangoDB 2.3 introduces the alternative variants for these operators:
  - `AND`: logical and
  - `OR`: logical or
  - `NOT`: negation

  The new syntax is just an alternative to the old syntax, allowing easier
  migration from SQL. The old syntax is still fully supported and will be.

* improved output of `ArangoStatement.parse()` and POST `/_api/query`

  If an AQL query can be parsed without problems, The return value of
  `ArangoStatement.parse()` now contains an attribute `ast` with the abstract
  syntax tree of the query (before optimizations). Though this is an internal
  representation of the query and is subject to change, it can be used to inspect
  how ArangoDB interprets a given query.

* improved `ArangoStatement.explain()` and POST `/_api/explain`

  The commands for explaining AQL queries have been improved.

* added command-line option `--javascript.v8-contexts` to control the number of
  V8 contexts created in arangod.

  Previously, the number of V8 contexts was equal to the number of server threads
  (as specified by option `--server.threads`).

  However, it may be sensible to create different amounts of threads and V8
  contexts. If the option is not specified, the number of V8 contexts created
  will be equal to the number of server threads. Thus no change in configuration
  is required to keep the old behavior.

  If you are using the default config files or merge them with your local config
  files, please review if the default number of server threads is okay in your
  environment. Additionally you should verify that the number of V8 contexts
  created (as specified in option `--javascript.v8-contexts`) is okay.

* the number of server.threads specified is now the minimum of threads
  started. There are situation in which threads are waiting for results of
  distributed database servers. In this case the number of threads is
  dynamically increased.

* removed index type "bitarray"

  Bitarray indexes were only half-way documented and integrated in previous versions
  of ArangoDB so their benefit was limited. The support for bitarray indexes has
  thus been removed in ArangoDB 2.3. It is not possible to create indexes of type
  "bitarray" with ArangoDB 2.3.

  When a collection is opened that contains a bitarray index definition created
  with a previous version of ArangoDB, ArangoDB will ignore it and log the following
  warning:

      index type 'bitarray' is not supported in this version of ArangoDB and is ignored

  Future versions of ArangoDB may automatically remove such index definitions so the
  warnings will eventually disappear.

* removed internal "_admin/modules/flush" in order to fix requireApp

* added basic support for handling binary data in Foxx

  Requests with binary payload can be processed in Foxx applications by
  using the new method `res.rawBodyBuffer()`. This will return the unparsed request
  body as a Buffer object.

  There is now also the method `req.requestParts()` available in Foxx to retrieve
  the individual components of a multipart HTTP request.

  Buffer objects can now be used when setting the response body of any Foxx action.
  Additionally, `res.send()` has been added as a convenience method for returning
  strings, JSON objects or buffers from a Foxx action:

      res.send("<p>some HTML</p>");
      res.send({ success: true });
      res.send(new Buffer("some binary data"));

  The convenience method `res.sendFile()` can now be used to easily return the
  contents of a file from a Foxx action:

      res.sendFile(applicationContext.foxxFilename("image.png"));

  `fs.write` now accepts not only strings but also Buffer objects as second parameter:

      fs.write(filename, "some data");
      fs.write(filename, new Buffer("some binary data"));

  `fs.readBuffer` can be used to return the contents of a file in a Buffer object.

* improved performance of insertion into non-unique hash indexes significantly in case
  many duplicate keys are used in the index

* issue #1042: set time zone in log output

  the command-line option `--log.use-local-time` was added to print dates and times in
  the server-local timezone instead of UTC

* command-line options that require a boolean value now validate the
  value given on the command-line

  This prevents issues if no value is specified for an option that
  requires a boolean value. For example, the following command-line would
  have caused trouble in 2.2, because `--server.endpoint` would have been
  used as the value for the `--server.disable-authentication` options
  (which requires a boolean value):

      arangod --server.disable-authentication --server.endpoint tcp://127.0.0.1:8529 data

  In 2.3, running this command will fail with an error and requires to
  be modified to:

      arangod --server.disable-authentication true --server.endpoint tcp://127.0.0.1:8529 data

* improved performance of CSV import in arangoimp

* fixed issue #1027: Stack traces are off-by-one

* fixed issue #1026: Modules loaded in different files within the same app
  should refer to the same module

* fixed issue #1025: Traversal not as expected in undirected graph

* added a _relation function in the general-graph module.

  This deprecated _directedRelation and _undirectedRelation.
  ArangoDB does not offer any constraints for undirected edges
  which caused some confusion of users how undirected relations
  have to be handled. Relation now only supports directed relations
  and the user can actively simulate undirected relations.

* changed return value of Foxx.applicationContext#collectionName:

  Previously, the function could return invalid collection names because
  invalid characters were not replaced in the application name prefix, only
  in the collection name passed.

  Now, the function replaces invalid characters also in the application name
  prefix, which might to slightly different results for application names that
  contained any characters outside the ranges [a-z], [A-Z] and [0-9].

* prevent XSS in AQL editor and logs view

* integrated tutorial into ArangoShell and web interface

* added option `--backslash-escape` for arangoimp when running CSV file imports

* front-end: added download feature for (filtered) documents

* front-end: added download feature for the results of a user query

* front-end: added function to move documents to another collection

* front-end: added sort-by attribute to the documents filter

* front-end: added sorting feature to database, graph management and user management view.

* issue #989: front-end: Databases view not refreshing after deleting a database

* issue #991: front-end: Database search broken

* front-end: added infobox which shows more information about a document (_id, _rev, _key) or
  an edge (_id, _rev, _key, _from, _to). The from and to attributes are clickable and redirect
  to their document location.

* front-end: added edit-mode for deleting multiple documents at the same time.

* front-end: added delete button to the detailed document/edge view.

* front-end: added visual feedback for saving documents/edges inside the editor (error/success).

* front-end: added auto-focusing for the first input field in a modal.

* front-end: added validation for user input in a modal.

* front-end: user defined queries are now stored inside the database and are bound to the current
  user, instead of using the local storage functionality of the browsers. The outcome of this is
  that user defined queries are now independently usable from any device. Also queries can now be
  edited through the standard document editor of the front-end through the _users collection.

* front-end: added import and export functionality for user defined queries.

* front-end: added new keywords and functions to the aql-editor theme

* front-end: applied tile-style to the graph view

* front-end: now using the new graph api including multi-collection support

* front-end: foxx apps are now deletable

* front-end: foxx apps are now installable and updateable through github, if github is their
  origin.

* front-end: added foxx app version control. Multiple versions of a single foxx app are now
  installable and easy to manage and are also arranged in groups.

* front-end: the user-set filter of a collection is now stored until the user navigates to
  another collection.

* front-end: fetching and filtering of documents, statistics, and query operations are now
  handled with asynchronous ajax calls.

* front-end: added progress indicator if the front-end is waiting for a server operation.

* front-end: fixed wrong count of documents in the documents view of a collection.

* front-end: fixed unexpected styling of the manage db view and navigation.

* front-end: fixed wrong handling of select fields in a modal view.

* front-end: fixed wrong positioning of some tooltips.

* automatically call `toJSON` function of JavaScript objects (if present)
  when serializing them into database documents. This change allows
  storing JavaScript date objects in the database in a sensible manner.


v2.2.7 (2014-11-19)
-------------------

* fixed issue #998: Incorrect application URL for non-system Foxx apps

* fixed issue #1079: AQL editor: keyword WITH in UPDATE query is not highlighted

* fix memory leak in cluster nodes

* fixed registration of AQL user-defined functions in Web UI (JS shell)

* fixed error display in Web UI for certain errors
  (now error message is printed instead of 'undefined')

* fixed issue #1059: bug in js module console

* fixed issue #1056: "fs": zip functions fail with passwords

* fixed issue #1063: Docs: measuring unit of --wal.logfile-size?

* fixed issue #1062: Docs: typo in 14.2 Example data


v2.2.6 (2014-10-20)
-------------------

* fixed issue #972: Compilation Issue

* fixed issue #743: temporary directories are now unique and one can read
  off the tool that created them, if empty, they are removed atexit

* Highly improved performance of all AQL GRAPH_* functions.

* Orphan collections in general graphs can now be found via GRAPH_VERTICES
  if either "any" or no direction is defined

* Fixed documentation for AQL function GRAPH_NEIGHBORS.
  The option "vertexCollectionRestriction" is meant to filter the target
  vertices only, and should not filter the path.

* Fixed a bug in GRAPH_NEIGHBORS which enforced only empty results
  under certain conditions


v2.2.5 (2014-10-09)
-------------------

* fixed issue #961: allow non-JSON values in undocument request bodies

* fixed issue 1028: libicu is now statically linked

* fixed cached lookups of collections on the server, which may have caused spurious
  problems after collection rename operations


v2.2.4 (2014-10-01)
-------------------

* fixed accessing `_from` and `_to` attributes in `collection.byExample` and
  `collection.firstExample`

  These internal attributes were not handled properly in the mentioned functions, so
  searching for them did not always produce documents

* fixed issue #1030: arangoimp 2.2.3 crashing, not logging on large Windows CSV file

* fixed issue #1025: Traversal not as expected in undirected graph

* fixed issue #1020

  This requires re-introducing the startup option `--database.force-sync-properties`.

  This option can again be used to force fsyncs of collection, index and database properties
  stored as JSON strings on disk in files named `parameter.json`. Syncing these files after
  a write may be necessary if the underlying storage does not sync file contents by itself
  in a "sensible" amount of time after a file has been written and closed.

  The default value is `true` so collection, index and database properties will always be
  synced to disk immediately. This affects creating, renaming and dropping collections as
  well as creating and dropping databases and indexes. Each of these operations will perform
  an additional fsync on the `parameter.json` file if the option is set to `true`.

  It might be sensible to set this option to `false` for workloads that create and drop a
  lot of collections (e.g. test runs).

  Document operations such as creating, updating and dropping documents are not affected
  by this option.

* fixed issue #1016: AQL editor bug

* fixed issue #1014: WITHIN function returns wrong distance

* fixed AQL shortest path calculation in function `GRAPH_SHORTEST_PATH` to return
  complete vertex objects instead of just vertex ids

* allow changing of attributes of documents stored in server-side JavaScript variables

  Previously, the following did not work:

      var doc = db.collection.document(key);
      doc._key = "abc"; // overwriting internal attributes not supported
      doc.value = 123;  // overwriting existing attributes not supported

  Now, modifying documents stored in server-side variables (e.g. `doc` in the above case)
  is supported. Modifying the variables will not update the documents in the database,
  but will modify the JavaScript object (which can be written back to the database using
  `db.collection.update` or `db.collection.replace`)

* fixed issue #997: arangoimp apparently doesn't support files >2gig on Windows

  large file support (requires using `_stat64` instead of `stat`) is now supported on
  Windows


v2.2.3 (2014-09-02)
-------------------

* added `around` for Foxx controller

* added `type` option for HTTP API `GET /_api/document?collection=...`

  This allows controlling the type of results to be returned. By default, paths to
  documents will be returned, e.g.

      [
        `/_api/document/test/mykey1`,
        `/_api/document/test/mykey2`,
        ...
      ]

  To return a list of document ids instead of paths, the `type` URL parameter can be
  set to `id`:

      [
        `test/mykey1`,
        `test/mykey2`,
        ...
      ]

  To return a list of document keys only, the `type` URL parameter can be set to `key`:

      [
        `mykey1`,
        `mykey2`,
        ...
      ]


* properly capitalize HTTP response header field names in case the `x-arango-async`
  HTTP header was used in a request.

* fixed several documentation issues

* speedup for several general-graph functions, AQL functions starting with `GRAPH_`
  and traversals


v2.2.2 (2014-08-08)
-------------------

* allow storing non-reserved attribute names starting with an underscore

  Previous versions of ArangoDB parsed away all attribute names that started with an
  underscore (e.g. `_test', '_foo', `_bar`) on all levels of a document (root level
  and sub-attribute levels). While this behavior was documented, it was unintuitive and
  prevented storing documents inside other documents, e.g.:

      {
        "_key" : "foo",
        "_type" : "mydoc",
        "references" : [
          {
            "_key" : "something",
            "_rev" : "...",
            "value" : 1
          },
          {
            "_key" : "something else",
            "_rev" : "...",
            "value" : 2
          }
        ]
      }

  In the above example, previous versions of ArangoDB removed all attributes and
  sub-attributes that started with underscores, meaning the embedded documents would lose
  some of their attributes. 2.2.2 should preserve such attributes, and will also allow
  storing user-defined attribute names on the top-level even if they start with underscores
  (such as `_type` in the above example).

* fix conversion of JavaScript String, Number and Boolean objects to JSON.

  Objects created in JavaScript using `new Number(...)`, `new String(...)`, or
  `new Boolean(...)` were not converted to JSON correctly.

* fixed a race condition on task registration (i.e. `require("org/arangodb/tasks").register()`)

  this race condition led to undefined behavior when a just-created task with no offset and
  no period was instantly executed and deleted by the task scheduler, before the `register`
  function returned to the caller.

* changed run-tests.sh to execute all suitable tests.

* switch to new version of gyp

* fixed upgrade button


v2.2.1 (2014-07-24)
-------------------

* fixed hanging write-ahead log recovery for certain cases that involved dropping
  databases

* fixed issue with --check-version: when creating a new database the check failed

* issue #947 Foxx applicationContext missing some properties

* fixed issue with --check-version: when creating a new database the check failed

* added startup option `--wal.suppress-shape-information`

  Setting this option to `true` will reduce memory and disk space usage and require
  less CPU time when modifying documents or edges. It should therefore be turned on
  for standalone ArangoDB servers. However, for servers that are used as replication
  masters, setting this option to `true` will effectively disable the usage of the
  write-ahead log for replication, so it should be set to `false` for any replication
  master servers.

  The default value for this option is `false`.

* added optional `ttl` attribute to specify result cursor expiration for HTTP API method
  `POST /_api/cursor`

  The `ttl` attribute can be used to prevent cursor results from timing out too early.

* issue #947: Foxx applicationContext missing some properties

* (reported by Christian Neubauer):

  The problem was that in Google's V8, signed and unsigned chars are not always declared cleanly.
  so we need to force v8 to compile with forced signed chars which is done by the Flag:
    -fsigned-char
  at least it is enough to follow the instructions of compiling arango on rasperry
  and add "CFLAGS='-fsigned-char'" to the make command of V8 and remove the armv7=0

* Fixed a bug with the replication client. In the case of single document
  transactions the collection was not write locked.


v2.2.0 (2014-07-10)
-------------------

* The replication methods `logger.start`, `logger.stop` and `logger.properties` are
  no-ops in ArangoDB 2.2 as there is no separate replication logger anymore. Data changes
  are logged into the write-ahead log in ArangoDB 2.2, and not separately by the
  replication logger. The replication logger object is still there in ArangoDB 2.2 to
  ensure backwards-compatibility, however, logging cannot be started, stopped or
  configured anymore. Using any of these methods will do nothing.

  This also affects the following HTTP API methods:
  - `PUT /_api/replication/logger-start`
  - `PUT /_api/replication/logger-stop`
  - `GET /_api/replication/logger-config`
  - `PUT /_api/replication/logger-config`

  Using any of these methods is discouraged from now on as they will be removed in
  future versions of ArangoDB.

* INCOMPATIBLE CHANGE: replication of transactions has changed. Previously, transactions
  were logged on a master in one big block and shipped to a slave in one block, too.
  Now transactions will be logged and replicated as separate entries, allowing transactions
  to be bigger and also ensure replication progress.

  This change also affects the behavior of the `stop` method of the replication applier.
  If the replication applier is now stopped manually using the `stop` method and later
  restarted using the `start` method, any transactions that were unfinished at the
  point of stopping will be aborted on a slave, even if they later commit on the master.

  In ArangoDB 2.2, stopping the replication applier manually should be avoided unless the
  goal is to stop replication permanently or to do a full resync with the master anyway.
  If the replication applier still must be stopped, it should be made sure that the
  slave has fetched and applied all pending operations from a master, and that no
  extra transactions are started on the master before the `stop` command on the slave
  is executed.

  Replication of transactions in ArangoDB 2.2 might also lock the involved collections on
  the slave while a transaction is either committed or aborted on the master and the
  change has been replicated to the slave. This change in behavior may be important for
  slave servers that are used for read-scaling. In order to avoid long lasting collection
  locks on the slave, transactions should be kept small.

  The `_replication` system collection is not used anymore in ArangoDB 2.2 and its usage is
  discouraged.

* INCOMPATIBLE CHANGE: the figures reported by the `collection.figures` method
  now only reflect documents and data contained in the journals and datafiles of
  collections. Documents or deletions contained only in the write-ahead log will
  not influence collection figures until the write-ahead log garbage collection
  kicks in. The figures for a collection might therefore underreport the total
  resource usage of a collection.

  Additionally, the attributes `lastTick` and `uncollectedLogfileEntries` have been
  added to the result of the `figures` operation and the HTTP API method
  `PUT /_api/collection/figures`

* added `insert` method as an alias for `save`. Documents can now be inserted into
  a collection using either method:

      db.test.save({ foo: "bar" });
      db.test.insert({ foo: "bar" });

* added support for data-modification AQL queries

* added AQL keywords `INSERT`, `UPDATE`, `REPLACE` and `REMOVE` (and `WITH`) to
  support data-modification AQL queries.

  Unquoted usage of these keywords for attribute names in AQL queries will likely
  fail in ArangoDB 2.2. If any such attribute name needs to be used in a query, it
  should be enclosed in backticks to indicate the usage of a literal attribute
  name.

  For example, the following query will fail in ArangoDB 2.2 with a parse error:

      FOR i IN foo RETURN i.remove

  and needs to be rewritten like this:

      FOR i IN foo RETURN i.`remove`

* disallow storing of JavaScript objects that contain JavaScript native objects
  of type `Date`, `Function`, `RegExp` or `External`, e.g.

      db.test.save({ foo: /bar/ });
      db.test.save({ foo: new Date() });

  will now print

      Error: <data> cannot be converted into JSON shape: could not shape document

  Previously, objects of these types were silently converted into an empty object
  (i.e. `{ }`).

  To store such objects in a collection, explicitly convert them into strings
  like this:

      db.test.save({ foo: String(/bar/) });
      db.test.save({ foo: String(new Date()) });

* The replication methods `logger.start`, `logger.stop` and `logger.properties` are
  no-ops in ArangoDB 2.2 as there is no separate replication logger anymore. Data changes
  are logged into the write-ahead log in ArangoDB 2.2, and not separately by the
  replication logger. The replication logger object is still there in ArangoDB 2.2 to
  ensure backwards-compatibility, however, logging cannot be started, stopped or
  configured anymore. Using any of these methods will do nothing.

  This also affects the following HTTP API methods:
  - `PUT /_api/replication/logger-start`
  - `PUT /_api/replication/logger-stop`
  - `GET /_api/replication/logger-config`
  - `PUT /_api/replication/logger-config`

  Using any of these methods is discouraged from now on as they will be removed in
  future versions of ArangoDB.

* INCOMPATIBLE CHANGE: replication of transactions has changed. Previously, transactions
  were logged on a master in one big block and shipped to a slave in one block, too.
  Now transactions will be logged and replicated as separate entries, allowing transactions
  to be bigger and also ensure replication progress.

  This change also affects the behavior of the `stop` method of the replication applier.
  If the replication applier is now stopped manually using the `stop` method and later
  restarted using the `start` method, any transactions that were unfinished at the
  point of stopping will be aborted on a slave, even if they later commit on the master.

  In ArangoDB 2.2, stopping the replication applier manually should be avoided unless the
  goal is to stop replication permanently or to do a full resync with the master anyway.
  If the replication applier still must be stopped, it should be made sure that the
  slave has fetched and applied all pending operations from a master, and that no
  extra transactions are started on the master before the `stop` command on the slave
  is executed.

  Replication of transactions in ArangoDB 2.2 might also lock the involved collections on
  the slave while a transaction is either committed or aborted on the master and the
  change has been replicated to the slave. This change in behavior may be important for
  slave servers that are used for read-scaling. In order to avoid long lasting collection
  locks on the slave, transactions should be kept small.

  The `_replication` system collection is not used anymore in ArangoDB 2.2 and its usage is
  discouraged.

* INCOMPATIBLE CHANGE: the figures reported by the `collection.figures` method
  now only reflect documents and data contained in the journals and datafiles of
  collections. Documents or deletions contained only in the write-ahead log will
  not influence collection figures until the write-ahead log garbage collection
  kicks in. The figures for a collection might therefore underreport the total
  resource usage of a collection.

  Additionally, the attributes `lastTick` and `uncollectedLogfileEntries` have been
  added to the result of the `figures` operation and the HTTP API method
  `PUT /_api/collection/figures`

* added `insert` method as an alias for `save`. Documents can now be inserted into
  a collection using either method:

      db.test.save({ foo: "bar" });
      db.test.insert({ foo: "bar" });

* added support for data-modification AQL queries

* added AQL keywords `INSERT`, `UPDATE`, `REPLACE` and `REMOVE` (and `WITH`) to
  support data-modification AQL queries.

  Unquoted usage of these keywords for attribute names in AQL queries will likely
  fail in ArangoDB 2.2. If any such attribute name needs to be used in a query, it
  should be enclosed in backticks to indicate the usage of a literal attribute
  name.

  For example, the following query will fail in ArangoDB 2.2 with a parse error:

      FOR i IN foo RETURN i.remove

  and needs to be rewritten like this:

      FOR i IN foo RETURN i.`remove`

* disallow storing of JavaScript objects that contain JavaScript native objects
  of type `Date`, `Function`, `RegExp` or `External`, e.g.

      db.test.save({ foo: /bar/ });
      db.test.save({ foo: new Date() });

  will now print

      Error: <data> cannot be converted into JSON shape: could not shape document

  Previously, objects of these types were silently converted into an empty object
  (i.e. `{ }`).

  To store such objects in a collection, explicitly convert them into strings
  like this:

      db.test.save({ foo: String(/bar/) });
      db.test.save({ foo: String(new Date()) });

* honor startup option `--server.disable-statistics` when deciding whether or not
  to start periodic statistics collection jobs

  Previously, the statistics collection jobs were started even if the server was
  started with the `--server.disable-statistics` flag being set to `true`

* removed startup option `--random.no-seed`

  This option had no effect in previous versions of ArangoDB and was thus removed.

* removed startup option `--database.remove-on-drop`

  This option was used for debugging only.

* removed startup option `--database.force-sync-properties`

  This option is now superfluous as collection properties are now stored in the
  write-ahead log.

* introduced write-ahead log

  All write operations in an ArangoDB server instance are automatically logged
  to the server's write-ahead log. The write-ahead log is a set of append-only
  logfiles, and it is used in case of a crash recovery and for replication.
  Data from the write-ahead log will eventually be moved into the journals or
  datafiles of collections, allowing the server to remove older write-ahead log
  logfiles. Figures of collections will be updated when data are moved from the
  write-ahead log into the journals or datafiles of collections.

  Cross-collection transactions in ArangoDB should benefit considerably by this
  change, as less writes than in previous versions are required to ensure the data
  of multiple collections are atomically and durably committed. All data-modifying
  operations inside transactions (insert, update, remove) will write their
  operations into the write-ahead log directly, making transactions with multiple
  operations also require less physical memory than in previous versions of ArangoDB,
  that required all transaction data to fit into RAM.

  The `_trx` system collection is not used anymore in ArangoDB 2.2 and its usage is
  discouraged.

  The data in the write-ahead log can also be used in the replication context.
  The `_replication` collection that was used in previous versions of ArangoDB to
  store all changes on the server is not used anymore in ArangoDB 2.2. Instead,
  slaves can read from a master's write-ahead log to get informed about most
  recent changes. This removes the need to store data-modifying operations in
  both the actual place and the `_replication` collection.

* removed startup option `--server.disable-replication-logger`

  This option is superfluous in ArangoDB 2.2. There is no dedicated replication
  logger in ArangoDB 2.2. There is now always the write-ahead log, and it is also
  used as the server's replication log. Specifying the startup option
  `--server.disable-replication-logger` will do nothing in ArangoDB 2.2, but the
  option should not be used anymore as it might be removed in a future version.

* changed behavior of replication logger

  There is no dedicated replication logger in ArangoDB 2.2 as there is the
  write-ahead log now. The existing APIs for starting and stopping the replication
  logger still exist in ArangoDB 2.2 for downwards-compatibility, but calling
  the start or stop operations are no-ops in ArangoDB 2.2. When querying the
  replication logger status via the API, the server will always report that the
  replication logger is running. Configuring the replication logger is a no-op
  in ArangoDB 2.2, too. Changing the replication logger configuration has no
  effect. Instead, the write-ahead log configuration can be changed.

* removed MRuby integration for arangod

  ArangoDB had an experimental MRuby integration in some of the publish builds.
  This wasn't continuously developed, and so it has been removed in ArangoDB 2.2.

  This change has led to the following startup options being superfluous:

  - `--ruby.gc-interval`
  - `--ruby.action-directory`
  - `--ruby.modules-path`
  - `--ruby.startup-directory`

  Specifying these startup options will do nothing in ArangoDB 2.2, but the
  options should be avoided from now on as they might be removed in future versions.

* reclaim index memory when last document in collection is deleted

  Previously, deleting documents from a collection did not lead to index sizes being
  reduced. Instead, the already allocated index memory was re-used when a collection
  was refilled.

  Now, index memory for primary indexes and hash indexes is reclaimed instantly when
  the last document from a collection is removed.

* inlined and optimized functions in hash indexes

* added AQL TRANSLATE function

  This function can be used to perform lookups from static lists, e.g.

      LET countryNames = { US: "United States", UK: "United Kingdom", FR: "France" }
      RETURN TRANSLATE("FR", countryNames)

* fixed datafile debugger

* fixed check-version for empty directory

* moved try/catch block to the top of routing chain

* added mountedApp function for foxx-manager

* fixed issue #883: arango 2.1 - when starting multi-machine cluster, UI web
  does not change to cluster overview

* fixed dfdb: should not start any other V8 threads

* cleanup of version-check, added module org/arangodb/database-version,
  added --check-version option

* fixed issue #881: [2.1.0] Bombarded (every 10 sec or so) with
  "WARNING format string is corrupt" when in non-system DB Dashboard

* specialized primary index implementation to allow faster hash table
  rebuilding and reduce lookups in datafiles for the actual value of `_key`.

* issue #862: added `--overwrite` option to arangoimp

* removed number of property lookups for documents during AQL queries that
  access documents

* prevent buffering of long print results in arangosh's and arangod's print
  command

  this change will emit buffered intermediate print results and discard the
  output buffer to quickly deliver print results to the user, and to prevent
  constructing very large buffers for large results

* removed sorting of attribute names for use in a collection's shaper

  sorting attribute names was done on document insert to keep attributes
  of a collection in sorted order for faster comparisons. The sort order
  of attributes was only used in one particular and unlikely case, so it
  was removed. Collections with many different attribute names should
  benefit from this change by faster inserts and slightly less memory usage.

* fixed a bug in arangodump which got the collection name in _from and _to
  attributes of edges wrong (all were "_unknown")

* fixed a bug in arangorestore which did not recognize wrong _from and _to
  attributes of edges

* improved error detection and reporting in arangorestore


v2.1.1 (2014-06-06)
-------------------

* fixed dfdb: should not start any other V8 threads

* signature for collection functions was modified

  The basic change was the substitution of the input parameter of the
  function by an generic options object which can contain multiple
  option parameter of the function.
  Following functions were modified
  remove
  removeBySample
  replace
  replaceBySample
  update
  updateBySample

  Old signature is yet supported but it will be removed in future versions

v2.1.0 (2014-05-29)
-------------------

* implemented upgrade procedure for clusters

* fixed communication issue with agency which prevented reconnect
  after an agent failure

* fixed cluster dashboard in the case that one but not all servers
  in the cluster are down

* fixed a bug with coordinators creating local database objects
  in the wrong order (_system needs to be done first)

* improved cluster dashboard


v2.1.0-rc2 (2014-05-25)
-----------------------

* fixed issue #864: Inconsistent behavior of AQL REVERSE(list) function


v2.1.0-rc1 (XXXX-XX-XX)
-----------------------

* added server-side periodic task management functions:

  - require("org/arangodb/tasks").register(): registers a periodic task
  - require("org/arangodb/tasks").unregister(): unregisters and removes a
    periodic task
  - require("org/arangodb/tasks").get(): retrieves a specific tasks or all
    existing tasks

  the previous undocumented function `internal.definePeriodic` is now
  deprecated and will be removed in a future release.

* decrease the size of some seldom used system collections on creation.

  This will make these collections use less disk space and mapped memory.

* added AQL date functions

* added AQL FLATTEN() list function

* added index memory statistics to `db.<collection>.figures()` function

  The `figures` function will now return a sub-document `indexes`, which lists
  the number of indexes in the `count` sub-attribute, and the total memory
  usage of the indexes in bytes in the `size` sub-attribute.

* added AQL CURRENT_DATABASE() function

  This function returns the current database's name.

* added AQL CURRENT_USER() function

  This function returns the current user from an AQL query. The current user is the
  username that was specified in the `Authorization` HTTP header of the request. If
  authentication is turned off or the query was executed outside a request context,
  the function will return `null`.

* fixed issue #796: Searching with newline chars broken?

  fixed slightly different handling of backslash escape characters in a few
  AQL functions. Now handling of escape sequences should be consistent, and
  searching for newline characters should work the same everywhere

* added OpenSSL version check for configure

  It will report all OpenSSL versions < 1.0.1g as being too old.
  `configure` will only complain about an outdated OpenSSL version but not stop.

* require C++ compiler support (requires g++ 4.8, clang++ 3.4 or Visual Studio 13)

* less string copying returning JSONified documents from ArangoDB, e.g. via
  HTTP GET `/_api/document/<collection>/<document>`

* issue #798: Lower case http headers from arango

  This change allows returning capitalized HTTP headers, e.g.
  `Content-Length` instead of `content-length`.
  The HTTP spec says that headers are case-insensitive, but
  in fact several clients rely on a specific case in response
  headers.
  This change will capitalize HTTP headers if the `X-Arango-Version`
  request header is sent by the client and contains a value of at
  least `20100` (for version 2.1). The default value for the
  compatibility can also be set at server start, using the
  `--server.default-api-compatibility` option.

* simplified usage of `db._createStatement()`

  Previously, the function could not be called with a query string parameter as
  follows:

      db._createStatement(queryString);

  Calling it as above resulted in an error because the function expected an
  object as its parameter. From now on, it's possible to call the function with
  just the query string.

* make ArangoDB not send back a `WWW-Authenticate` header to a client in case the
  client sends the `X-Omit-WWW-Authenticate` HTTP header.

  This is done to prevent browsers from showing their built-in HTTP authentication
  dialog for AJAX requests that require authentication.
  ArangoDB will still return an HTTP 401 (Unauthorized) if the request doesn't
  contain valid credentials, but it will omit the `WWW-Authenticate` header,
  allowing clients to bypass the browser's authentication dialog.

* added REST API method HTTP GET `/_api/job/job-id` to query the status of an
  async job without potentially fetching it from the list of done jobs

* fixed non-intuitive behavior in jobs API: previously, querying the status
  of an async job via the API HTTP PUT `/_api/job/job-id` removed a currently
  executing async job from the list of queryable jobs on the server.
  Now, when querying the result of an async job that is still executing,
  the job is kept in the list of queryable jobs so its result can be fetched
  by a subsequent request.

* use a new data structure for the edge index of an edge collection. This
  improves the performance for the creation of the edge index and in
  particular speeds up removal of edges in graphs. Note however that
  this change might change the order in which edges starting at
  or ending in a vertex are returned. However, this order was never
  guaranteed anyway and it is not sensible to guarantee any particular
  order.

* provide a size hint to edge and hash indexes when initially filling them
  this will lead to less re-allocations when populating these indexes

  this may speed up building indexes when opening an existing collection

* don't requeue identical context methods in V8 threads in case a method is
  already registered

* removed arangod command line option `--database.remove-on-compacted`

* export the sort attribute for graph traversals to the HTTP interface

* add support for arangodump/arangorestore for clusters


v2.0.8 (XXXX-XX-XX)
-------------------

* fixed too-busy iteration over skiplists

  Even when a skiplist query was restricted by a limit clause, the skiplist
  index was queried without the limit. this led to slower-than-necessary
  execution times.

* fixed timeout overflows on 32 bit systems

  this bug has led to problems when select was called with a high timeout
  value (2000+ seconds) on 32bit systems that don't have a forgiving select
  implementation. when the call was made on these systems, select failed
  so no data would be read or sent over the connection

  this might have affected some cluster-internal operations.

* fixed ETCD issues on 32 bit systems

  ETCD was non-functional on 32 bit systems at all. The first call to the
  watch API crashed it. This was because atomic operations worked on data
  structures that were not properly aligned on 32 bit systems.

* fixed issue #848: db.someEdgeCollection.inEdge does not return correct
  value when called the 2nd time after a .save to the edge collection


v2.0.7 (2014-05-05)
-------------------

* issue #839: Foxx Manager missing "unfetch"

* fixed a race condition at startup

  this fixes undefined behavior in case the logger was involved directly at
  startup, before the logger initialization code was called. This should have
  occurred only for code that was executed before the invocation of main(),
  e.g. during ctor calls of statically defined objects.


v2.0.6 (2014-04-22)
-------------------

* fixed issue #835: arangosh doesn't show correct database name



v2.0.5 (2014-04-21)
-------------------

* Fixed a caching problem in IE JS Shell

* added cancelation for async jobs

* upgraded to new gyp for V8

* new Windows installer


v2.0.4 (2014-04-14)
-------------------

* fixed cluster authentication front-end issues for Firefox and IE, there are
  still problems with Chrome


v2.0.3 (2014-04-14)
-------------------

* fixed AQL optimizer bug

* fixed front-end issues

* added password change dialog


v2.0.2 (2014-04-06)
-------------------

* during cluster startup, do not log (somewhat expected) connection errors with
  log level error, but with log level info

* fixed dashboard modals

* fixed connection check for cluster planning front end: firefox does
  not support async:false

* document how to persist a cluster plan in order to relaunch an existing
  cluster later


v2.0.1 (2014-03-31)
-------------------

* make ArangoDB not send back a `WWW-Authenticate` header to a client in case the
  client sends the `X-Omit-WWW-Authenticate` HTTP header.

  This is done to prevent browsers from showing their built-in HTTP authentication
  dialog for AJAX requests that require authentication.
  ArangoDB will still return an HTTP 401 (Unauthorized) if the request doesn't
  contain valid credentials, but it will omit the `WWW-Authenticate` header,
  allowing clients to bypass the browser's authentication dialog.

* fixed isses in arango-dfdb:

  the dfdb was not able to unload certain system collections, so these couldn't be
  inspected with the dfdb sometimes. Additionally, it did not truncate corrupt
  markers from datafiles under some circumstances

* added `changePassword` attribute for users

* fixed non-working "save" button in collection edit view of web interface
  clicking the save button did nothing. one had to press enter in one of the input
  fields to send modified form data

* fixed V8 compile error on MacOS X

* prevent `body length: -9223372036854775808` being logged in development mode for
  some Foxx HTTP responses

* fixed several bugs in web interface dashboard

* fixed issue #783: coffee script not working in manifest file

* fixed issue #783: coffee script not working in manifest file

* fixed issue #781: Cant save current query from AQL editor ui

* bumped version in `X-Arango-Version` compatibility header sent by arangosh and other
  client tools from `1.5` to `2.0`.

* fixed startup options for arango-dfdb, added details option for arango-dfdb

* fixed display of missing error messages and codes in arangosh

* when creating a collection via the web interface, the collection type was always
  "document", regardless of the user's choice


v2.0.0 (2014-03-10)
-------------------

* first 2.0 release


v2.0.0-rc2 (2014-03-07)
-----------------------

* fixed cluster authorization


v2.0.0-rc1 (2014-02-28)
-----------------------

* added sharding :-)

* added collection._dbName attribute to query the name of the database from a collection

  more detailed documentation on the sharding and cluster features can be found in the user
  manual, section **Sharding**

* INCOMPATIBLE CHANGE: using complex values in AQL filter conditions with operators other
  than equality (e.g. >=, >, <=, <) will disable usage of skiplist indexes for filter
  evaluation.

  For example, the following queries will be affected by change:

      FOR doc IN docs FILTER doc.value < { foo: "bar" } RETURN doc
      FOR doc IN docs FILTER doc.value >= [ 1, 2, 3 ] RETURN doc

  The following queries will not be affected by the change:

      FOR doc IN docs FILTER doc.value == 1 RETURN doc
      FOR doc IN docs FILTER doc.value == "foo" RETURN doc
      FOR doc IN docs FILTER doc.value == [ 1, 2, 3 ] RETURN doc
      FOR doc IN docs FILTER doc.value == { foo: "bar" } RETURN doc

* INCOMPATIBLE CHANGE: removed undocumented method `collection.saveOrReplace`

  this feature was never advertised nor documented nor tested.

* INCOMPATIBLE CHANGE: removed undocumented REST API method `/_api/simple/BY-EXAMPLE-HASH`

  this feature was never advertised nor documented nor tested.

* added explicit startup parameter `--server.reuse-address`

  This flag can be used to control whether sockets should be acquired with the SO_REUSEADDR
  flag.

  Regardless of this setting, sockets on Windows are always acquired using the
  SO_EXCLUSIVEADDRUSE flag.

* removed undocumented REST API method GET `/_admin/database-name`

* added user validation API at POST `/_api/user/<username>`

* slightly improved users management API in `/_api/user`:

  Previously, when creating a new user via HTTP POST, the username needed to be
  passed in an attribute `username`. When users were returned via this API,
  the usernames were returned in an attribute named `user`. This was slightly
  confusing and was changed in 2.0 as follows:

  - when adding a user via HTTP POST, the username can be specified in an attribute
  `user`. If this attribute is not used, the API will look into the attribute `username`
  as before and use that value.
  - when users are returned via HTTP GET, the usernames are still returned in an
    attribute `user`.

  This change should be fully downwards-compatible with the previous version of the API.

* added AQL SLICE function to extract slices from lists

* made module loader more node compatible

* the startup option `--javascript.package-path` for arangosh is now deprecated and does
  nothing. Using it will not cause an error, but the option is ignored.

* added coffee script support

* Several UI improvements.

* Exchanged icons in the graphviewer toolbar

* always start networking and HTTP listeners when starting the server (even in
  console mode)

* allow vertex and edge filtering with user-defined functions in TRAVERSAL,
  TRAVERSAL_TREE and SHORTEST_PATH AQL functions:

      // using user-defined AQL functions for edge and vertex filtering
      RETURN TRAVERSAL(friends, friendrelations, "friends/john", "outbound", {
        followEdges: "myfunctions::checkedge",
        filterVertices: "myfunctions::checkvertex"
      })

      // using the following custom filter functions
      var aqlfunctions = require("org/arangodb/aql/functions");
      aqlfunctions.register("myfunctions::checkedge", function (config, vertex, edge, path) {
        return (edge.type !== 'dislikes'); // don't follow these edges
      }, false);

      aqlfunctions.register("myfunctions::checkvertex", function (config, vertex, path) {
        if (vertex.isDeleted || ! vertex.isActive) {
          return [ "prune", "exclude" ]; // exclude these and don't follow them
        }
        return [ ]; // include everything else
      }, false);

* fail if invalid `strategy`, `order` or `itemOrder` attribute values
  are passed to the AQL TRAVERSAL function. Omitting these attributes
  is not considered an error, but specifying an invalid value for any
  of these attributes will make an AQL query fail.

* issue #751: Create database through API should return HTTP status code 201

  By default, the server now returns HTTP 201 (created) when creating a new
  database successfully. To keep compatibility with older ArangoDB versions, the
  startup parameter `--server.default-api-compatibility` can be set to a value
  of `10400` to indicate API compatibility with ArangoDB 1.4. The compatibility
  can also be enforced by setting the `X-Arango-Version` HTTP header in a
  client request to this API on a per-request basis.

* allow direct access from the `db` object to collections whose names start
  with an underscore (e.g. db._users).

  Previously, access to such collections via the `db` object was possible from
  arangosh, but not from arangod (and thus Foxx and actions). The only way
  to access such collections from these places was via the `db._collection(<name>)`
  workaround.

* allow `\n` (as well as `\r\n`) as line terminator in batch requests sent to
  `/_api/batch` HTTP API.

* use `--data-binary` instead of `--data` parameter in generated cURL examples

* issue #703: Also show path of logfile for fm.config()

* issue #675: Dropping a collection used in "graph" module breaks the graph

* added "static" Graph.drop() method for graphs API

* fixed issue #695: arangosh server.password error

* use pretty-printing in `--console` mode by default

* simplified ArangoDB startup options

  Some startup options are now superfluous or their usage is simplified. The
  following options have been changed:

  * `--javascript.modules-path`: this option has been removed. The modules paths
    are determined by arangod and arangosh automatically based on the value of
    `--javascript.startup-directory`.

    If the option is set on startup, it is ignored so startup will not abort with
    an error `unrecognized option`.

  * `--javascript.action-directory`: this option has been removed. The actions
    directory is determined by arangod automatically based on the value of
    `--javascript.startup-directory`.

    If the option is set on startup, it is ignored so startup will not abort with
    an error `unrecognized option`.

  * `--javascript.package-path`: this option is still available but it is not
    required anymore to set the standard package paths (e.g. `js/npm`). arangod
    will automatically use this standard package path regardless of whether it
    was specified via the options.

    It is possible to use this option to add additional package paths to the
    standard value.

  Configuration files included with arangod are adjusted accordingly.

* layout of the graphs tab adapted to better fit with the other tabs

* database selection is moved to the bottom right corner of the web interface

* removed priority queue index type

  this feature was never advertised nor documented nor tested.

* display internal attributes in document source view of web interface

* removed separate shape collections

  When upgrading to ArangoDB 2.0, existing collections will be converted to include
  shapes and attribute markers in the datafiles instead of using separate files for
  shapes.

  When a collection is converted, existing shapes from the SHAPES directory will
  be written to a new datafile in the collection directory, and the SHAPES directory
  will be removed afterwards.

  This saves up to 2 MB of memory and disk space for each collection
  (savings are higher, the less different shapes there are in a collection).
  Additionally, one less file descriptor per opened collection will be used.

  When creating a new collection, the amount of sync calls may be reduced. The same
  may be true for documents with yet-unknown shapes. This may help performance
  in these cases.

* added AQL functions `NTH` and `POSITION`

* added signal handler for arangosh to save last command in more cases

* added extra prompt placeholders for arangosh:
  - `%e`: current endpoint
  - `%u`: current user

* added arangosh option `--javascript.gc-interval` to control amount of
  garbage collection performed by arangosh

* fixed issue #651: Allow addEdge() to take vertex ids in the JS library

* removed command-line option `--log.format`

  In previous versions, this option did not have an effect for most log messages, so
  it got removed.

* removed C++ logger implementation

  Logging inside ArangoDB is now done using the LOG_XXX() macros. The LOGGER_XXX()
  macros are gone.

* added collection status "loading"


v1.4.16 (XXXX-XX-XX)
--------------------

* fixed too eager datafile deletion

  this issue could have caused a crash when the compaction had marked datafiles as obsolete
  and they were removed while "old" temporary query results still pointed to the old datafile
  positions

* fixed issue #826: Replication fails when a collection's configuration changes


v1.4.15 (2014-04-19)
--------------------

* bugfix for AQL query optimizer

  the following type of query was too eagerly optimized, leading to errors in code-generation:

      LET a = (FOR i IN [] RETURN i) LET b = (FOR i IN [] RETURN i) RETURN 1

  the problem occurred when both lists in the subqueries were empty. In this case invalid code
  was generated and the query couldn't be executed.


v1.4.14 (2014-04-05)
--------------------

* fixed race conditions during shape / attribute insertion

  A race condition could have led to spurious `cannot find attribute #xx` or
  `cannot find shape #xx` (where xx is a number) warning messages being logged
  by the server. This happened when a new attribute was inserted and at the same
  time was queried by another thread.

  Also fixed a race condition that may have occurred when a thread tried to
  access the shapes / attributes hash tables while they were resized. In this
  cases, the shape / attribute may have been hashed to a wrong slot.

* fixed a memory barrier / cpu synchronization problem with libev, affecting
  Windows with Visual Studio 2013 (probably earlier versions are affected, too)

  The issue is described in detail here:
  http://lists.schmorp.de/pipermail/libev/2014q1/002318.html


v1.4.13 (2014-03-14)
--------------------

* added diagnostic output for Foxx application upload

* allow dump & restore from ArangoDB 1.4 with an ArangoDB 2.0 server

* allow startup options `temp-path` and `default-language` to be specified from the arangod
  configuration file and not only from the command line

* fixed too eager compaction

  The compaction will now wait for several seconds before trying to re-compact the same
  collection. Additionally, some other limits have been introduced for the compaction.


v1.4.12 (2014-03-05)
--------------------

* fixed display bug in web interface which caused the following problems:
  - documents were displayed in web interface as being empty
  - document attributes view displayed many attributes with content "undefined"
  - document source view displayed many attributes with name "TYPEOF" and value "undefined"
  - an alert popping up in the browser with message "Datatables warning..."

* re-introduced old-style read-write locks to supports Windows versions older than
  Windows 2008R2 and Windows 7. This should re-enable support for Windows Vista and
  Windows 2008.


v1.4.11 (2014-02-27)
--------------------

* added SHORTEST_PATH AQL function

  this calculates the shortest paths between two vertices, using the Dijkstra
  algorithm, employing a min-heap

  By default, ArangoDB does not know the distance between any two vertices and
  will use a default distance of 1. A custom distance function can be registered
  as an AQL user function to make the distance calculation use any document
  attributes or custom logic:

      RETURN SHORTEST_PATH(cities, motorways, "cities/CGN", "cities/MUC", "outbound", {
        paths: true,
        distance: "myfunctions::citydistance"
      })

      // using the following custom distance function
      var aqlfunctions = require("org/arangodb/aql/functions");
      aqlfunctions.register("myfunctions::distance", function (config, vertex1, vertex2, edge) {
        return Math.sqrt(Math.pow(vertex1.x - vertex2.x) + Math.pow(vertex1.y - vertex2.y));
      }, false);

* fixed bug in Graph.pathTo function

* fixed small memleak in AQL optimizer

* fixed access to potentially uninitialized variable when collection had a cap constraint


v1.4.10 (2014-02-21)
--------------------

* fixed graph constructor to allow graph with some parameter to be used

* added node.js "events" and "stream"

* updated npm packages

* added loading of .json file

* Fixed http return code in graph api with waitForSync parameter.

* Fixed documentation in graph, simple and index api.

* removed 2 tests due to change in ruby library.

* issue #756: set access-control-expose-headers on CORS response

  the following headers are now whitelisted by ArangoDB in CORS responses:
  - etag
  - content-encoding
  - content-length
  - location
  - server
  - x-arango-errors
  - x-arango-async-id


v1.4.9 (2014-02-07)
-------------------

* return a document's current etag in response header for HTTP HEAD requests on
  documents that return an HTTP 412 (precondition failed) error. This allows
  retrieving the document's current revision easily.

* added AQL function `SKIPLIST` to directly access skiplist indexes from AQL

  This is a shortcut method to use a skiplist index for retrieving specific documents in
  indexed order. The function capability is rather limited, but it may be used
  for several cases to speed up queries. The documents are returned in index order if
  only one condition is used.

      /* return all documents with mycollection.created > 12345678 */
      FOR doc IN SKIPLIST(mycollection, { created: [[ '>', 12345678 ]] })
        RETURN doc

      /* return first document with mycollection.created > 12345678 */
      FOR doc IN SKIPLIST(mycollection, { created: [[ '>', 12345678 ]] }, 0, 1)
        RETURN doc

      /* return all documents with mycollection.created between 12345678 and 123456790 */
      FOR doc IN SKIPLIST(mycollection, { created: [[ '>', 12345678 ], [ '<=', 123456790 ]] })
        RETURN doc

      /* return all documents with mycollection.a equal 1 and .b equal 2 */
      FOR doc IN SKIPLIST(mycollection, { a: [[ '==', 1 ]], b: [[ '==', 2 ]] })
        RETURN doc

  The function requires a skiplist index with the exact same attributes to
  be present on the specified collection. All attributes present in the skiplist
  index must be specified in the conditions specified for the `SKIPLIST` function.
  Attribute declaration order is important, too: attributes must be specified in the
  same order in the condition as they have been declared in the skiplist index.

* added command-line option `--server.disable-authentication-unix-sockets`

  with this option, authentication can be disabled for all requests coming
  in via UNIX domain sockets, enabling clients located on the same host as
  the ArangoDB server to connect without authentication.
  Other connections (e.g. TCP/IP) are not affected by this option.

  The default value for this option is `false`.
  Note: this option is only supported on platforms that support Unix domain
  sockets.

* call global arangod instance destructor on shutdown

* issue #755: TRAVERSAL does not use strategy, order and itemOrder options

  these options were not honored when configuring a traversal via the AQL
  TRAVERSAL function. Now, these options are used if specified.

* allow vertex and edge filtering with user-defined functions in TRAVERSAL,
  TRAVERSAL_TREE and SHORTEST_PATH AQL functions:

      // using user-defined AQL functions for edge and vertex filtering
      RETURN TRAVERSAL(friends, friendrelations, "friends/john", "outbound", {
        followEdges: "myfunctions::checkedge",
        filterVertices: "myfunctions::checkvertex"
      })

      // using the following custom filter functions
      var aqlfunctions = require("org/arangodb/aql/functions");
      aqlfunctions.register("myfunctions::checkedge", function (config, vertex, edge, path) {
        return (edge.type !== 'dislikes'); // don't follow these edges
      }, false);

      aqlfunctions.register("myfunctions::checkvertex", function (config, vertex, path) {
        if (vertex.isDeleted || ! vertex.isActive) {
          return [ "prune", "exclude" ]; // exclude these and don't follow them
        }
        return [ ]; // include everything else
      }, false);

* issue #748: add vertex filtering to AQL's TRAVERSAL[_TREE]() function


v1.4.8 (2014-01-31)
-------------------

* install foxx apps in the web interface

* fixed a segfault in the import API


v1.4.7 (2014-01-23)
-------------------

* issue #744: Add usage example arangoimp from Command line

* issue #738: added __dirname, __filename pseudo-globals. Fixes #733. (@by pluma)

* mount all Foxx applications in system apps directory on startup


v1.4.6 (2014-01-20)
-------------------

* issue #736: AQL function to parse collection and key from document handle

* added fm.rescan() method for Foxx-Manager

* fixed issue #734: foxx cookie and route problem

* added method `fm.configJson` for arangosh

* include `startupPath` in result of API `/_api/foxx/config`


v1.4.5 (2014-01-15)
-------------------

* fixed issue #726: Alternate Windows Install Method

* fixed issue #716: dpkg -P doesn't remove everything

* fixed bugs in description of HTTP API `_api/index`

* fixed issue #732: Rest API GET revision number

* added missing documentation for several methods in HTTP API `/_api/edge/...`

* fixed typos in description of HTTP API `_api/document`

* defer evaluation of AQL subqueries and logical operators (lazy evaluation)

* Updated font in WebFrontend, it now contains a version that renders properly on Windows

* generally allow function return values as call parameters to AQL functions

* fixed potential deadlock in global context method execution

* added override file "arangod.conf.local" (and co)


v1.4.4 (2013-12-24)
-------------------

* uid and gid are now set in the scripts, there is no longer a separate config file for
  arangod when started from a script

* foxx-manager is now an alias for arangosh

* arango-dfdb is now an alias for arangod, moved from bin to sbin

* changed from readline to linenoise for Windows

* added --install-service and --uninstall-service for Windows

* removed --daemon and --supervisor for Windows

* arangosh and arangod now uses the config-file which maps the binary name, i. e. if you
  rename arangosh to foxx-manager it will use the config file foxx-manager.conf

* fixed lock file for Windows

* fixed issue #711, #687: foxx-manager throws internal errors

* added `--server.ssl-protocol` option for client tools
  this allows connecting from arangosh, arangoimp, arangoimp etc. to an ArangoDB
  server that uses a non-default value for `--server.ssl-protocol`. The default
  value for the SSL protocol is 4 (TLSv1). If the server is configured to use a
  different protocol, it was not possible to connect to it with the client tools.

* added more detailed request statistics

  This adds the number of async-executed HTTP requests plus the number of HTTP
  requests per individual HTTP method type.

* added `--force` option for arangorestore
  this option allows continuing a restore operation even if the server reports errors
  in the middle of the restore operation

* better error reporting for arangorestore
  in case the server returned an HTTP error, arangorestore previously reported this
  error as `internal error` without any details only. Now server-side errors are
  reported by arangorestore with the server's error message

* include more system collections in dumps produced by arangodump
  previously some system collections were intentionally excluded from dumps, even if the
  dump was run with `--include-system-collections`. for example, the collections `_aal`,
  `_modules`, `_routing`, and `_users` were excluded. This makes sense in a replication
  context but not always in a dump context.
  When specifying `--include-system-collections`, arangodump will now include the above-
  mentioned collections in the dump, too. Some other system collections are still excluded
  even when the dump is run with `--include-system-collections`, for example `_replication`
  and `_trx`.

* fixed issue #701: ArangoStatement undefined in arangosh

* fixed typos in configuration files


v1.4.3 (2013-11-25)
-------------------

* fixed a segfault in the AQL optimizer, occurring when a constant non-list value was
  used on the right-hand side of an IN operator that had a collection attribute on the
  left-hand side

* issue #662:

  Fixed access violation errors (crashes) in the Windows version, occurring under some
  circumstances when accessing databases with multiple clients in parallel

* fixed issue #681: Problem with ArchLinux PKGBUILD configuration


v1.4.2 (2013-11-20)
-------------------

* fixed issue #669: Tiny documentation update

* ported Windows version to use native Windows API SRWLocks (slim read-write locks)
  and condition variables instead of homemade versions

  MSDN states the following about the compatibility of SRWLocks and Condition Variables:

      Minimum supported client:
      Windows Server 2008 [desktop apps | Windows Store apps]

      Minimum supported server:
      Windows Vista [desktop apps | Windows Store apps]

* fixed issue #662: ArangoDB on Windows hanging

  This fixes a deadlock issue that occurred on Windows when documents were written to
  a collection at the same time when some other thread tried to drop the collection.

* fixed file-based logging in Windows

  the logger complained on startup if the specified log file already existed

* fixed startup of server in daemon mode (`--daemon` startup option)

* fixed a segfault in the AQL optimizer

* issue #671: Method graph.measurement does not exist

* changed Windows condition variable implementation to use Windows native
  condition variables

  This is an attempt to fix spurious Windows hangs as described in issue #662.

* added documentation for JavaScript traversals

* added --code-page command-line option for Windows version of arangosh

* fixed a problem when creating edges via the web interface.

  The problem only occurred if a collection was created with type "document
  collection" via the web interface, and afterwards was dropped and re-created
  with type "edge collection". If the web interface page was not reloaded,
  the old collection type (document) was cached, making the subsequent creation
  of edges into the (seeming-to-be-document) collection fail.

  The fix is to not cache the collection type in the web interface. Users of
  an older version of the web interface can reload the collections page if they
  are affected.

* fixed a caching problem in arangosh: if a collection was created using the web
  interface, and then removed via arangosh, arangosh did not actually drop the
  collection due to caching.

  Because the `drop` operation was not carried out, this caused misleading error
  messages when trying to re-create the collection (e.g. `cannot create collection:
  duplicate name`).

* fixed ALT-introduced characters for arangosh console input on Windows

  The Windows readline port was not able to handle characters that are built
  using CTRL or ALT keys. Regular characters entered using the CTRL or ALT keys
  were silently swallowed and not passed to the terminal input handler.

  This did not seem to cause problems for the US keyboard layout, but was a
  severe issue for keyboard layouts that require the ALT (or ALT-GR) key to
  construct characters. For example, entering the character `{` with a German
  keyboard layout requires pressing ALT-GR + 9.

* fixed issue #665: Hash/skiplist combo madness bit my ass

  this fixes a problem with missing/non-deterministic rollbacks of inserts in
  case of a unique constraint violation into a collection with multiple secondary
  indexes (with at least one of them unique)

* fixed issue #664: ArangoDB installer on Windows requires drive c:

* partly fixed issue #662: ArangoDB on Windows hanging

  This fixes dropping databases on Windows. In previous 1.4 versions on Windows,
  one shape collection file was not unloaded and removed when dropping a database,
  leaving one directory and one shape collection file in the otherwise-dropped
  database directory.

* fixed issue #660: updated documentation on indexes


v1.4.1 (2013-11-08)
-------------------

* performance improvements for skip-list deletes


v1.4.1-rc1 (2013-11-07)
-----------------------

* fixed issue #635: Web-Interface should have a "Databases" Menu for Management

* fixed issue #624: Web-Interface is missing a Database selector

* fixed segfault in bitarray query

* fixed issue #656: Cannot create unique index through web interface

* fixed issue #654: bitarray index makes server down

* fixed issue #653: Slow query

* fixed issue #650: Randomness of any() should be improved

* made AQL `DOCUMENT()` function polymorphic and work with just one parameter.

  This allows using the `DOCUMENT` function like this:

      DOCUMENT('users/john')
      DOCUMENT([ 'users/john', 'users/amy' ])

  in addition to the existing use cases:

      DOCUMENT(users, 'users/john')
      DOCUMENT(users, 'john')
      DOCUMENT(users, [ 'users/john' ])
      DOCUMENT(users, [ 'users/john', 'users/amy' ])
      DOCUMENT(users, [ 'john', 'amy' ])

* simplified usage of ArangoDB batch API

  It is not necessary anymore to send the batch boundary in the HTTP `Content-Type`
  header. Previously, the batch API expected the client to send a Content-Type header
  of`multipart/form-data; boundary=<some boundary value>`. This is still supported in
  ArangoDB 2.0, but clients can now also omit this header. If the header is not
  present in a client request, ArangoDB will ignore the request content type and
  read the MIME boundary from the beginning of the request body.

  This also allows using the batch API with the Swagger "Try it out" feature (which is
  not too good at sending a different or even dynamic content-type request header).

* added API method GET `/_api/database/user`

  This returns the list of databases a specific user can see without changing the
  username/passwd.

* issue #424: Documentation about IDs needs to be upgraded


v1.4.0 (2013-10-29)
-------------------

* fixed issue #648: /batch API is missing from Web Interface API Documentation (Swagger)

* fixed issue #647: Icon tooltips missing

* fixed issue #646: index creation in web interface

* fixed issue #645: Allow jumping from edge to linked vertices

* merged PR for issue #643: Some minor corrections and a link to "Downloads"

* fixed issue #642: Completion of error handling

* fixed issue #639: compiling v1.4 on maverick produces warnings on -Wstrict-null-sentinel

* fixed issue #634: Web interface bug: Escape does not always propagate

* fixed issue #620: added startup option `--server.default-api-compatibility`

  This adds the following changes to the ArangoDB server and clients:
  - the server provides a new startup option `--server.default-api-compatibility`.
    This option can be used to determine the compatibility of (some) server API
    return values. The value for this parameter is a server version number,
    calculated as follows: `10000 * major + 100 * minor` (e.g. `10400` for ArangoDB
    1.3). The default value is `10400` (1.4), the minimum allowed value is `10300`
    (1.3).

    When setting this option to a value lower than the current server version,
    the server might respond with old-style results to "old" clients, increasing
    compatibility with "old" (non-up-to-date) clients.

  - the server will on each incoming request check for an HTTP header
    `x-arango-version`. Clients can optionally set this header to the API
    version number they support. For example, if a client sends the HTTP header
    `x-arango-version: 10300`, the server will pick this up and might send ArangoDB
    1.3-style responses in some situations.

    Setting either the startup parameter or using the HTTP header (or both) allows
    running "old" clients with newer versions of ArangoDB, without having to adjust
    the clients too much.

  - the `location` headers returned by the server for the APIs `/_api/document/...`
    and `/_api/collection/...` will have different values depending on the used API
    version. If the API compatibility is `10300`, the `location` headers returned
    will look like this:

        location: /_api/document/....

    whereas when an API compatibility of `10400` or higher is used, the `location`
    headers will look like this:

        location: /_db/<database name>/_api/document/...

  Please note that even in the presence of this, old API versions still may not
  be supported forever by the server.

* fixed issue #643: Some minor corrections and a link to "Downloads" by @frankmayer

* started issue #642: Completion of error handling

* fixed issue #639: compiling v1.4 on maverick produces warnings on
  -Wstrict-null-sentinel

* fixed issue #621: Standard Config needs to be fixed

* added function to manage indexes (web interface)

* improved server shutdown time by signaling shutdown to applicationserver,
  logging, cleanup and compactor threads

* added foxx-manager `replace` command

* added foxx-manager `installed` command (a more intuitive alias for `list`)

* fixed issue #617: Swagger API is missing '/_api/version'

* fixed issue #615: Swagger API: Some commands have no parameter entry forms

* fixed issue #614: API : Typo in : Request URL /_api/database/current

* fixed issue #609: Graph viz tool - different background color

* fixed issue #608: arangosh config files - eventually missing in the manual

* fixed issue #607: Admin interface: no core documentation

* fixed issue #603: Aardvark Foxx App Manager

* fixed a bug in type-mapping between AQL user functions and the AQL layer

  The bug caused errors like the following when working with collection documents
  in an AQL user function:

      TypeError: Cannot assign to read only property '_id' of #<ShapedJson>

* create less system collections when creating a new database

  This is achieved by deferring collection creation until the collections are actually
  needed by ArangoDB. The following collections are affected by the change:
  - `_fishbowl`
  - `_structures`


v1.4.0-beta2 (2013-10-14)
-------------------------

* fixed compaction on Windows

  The compaction on Windows did not ftruncate the cleaned datafiles to a smaller size.
  This has been fixed so not only the content of the files is cleaned but also files
  are re-created with potentially smaller sizes.

* only the following system collections will be excluded from replication from now on:
  - `_replication`
  - `_trx`
  - `_users`
  - `_aal`
  - `_fishbowl`
  - `_modules`
  - `_routing`

  Especially the following system collections will now be included in replication:
  - `_aqlfunctions`
  - `_graphs`

  In previous versions of ArangoDB, all system collections were excluded from the
  replication.

  The change also caused a change in the replication logger and applier:
  in previous versions of ArangoDB, only a collection's id was logged for an operation.
  This has not caused problems for non-system collections but for system collections
  there ids might differ. In addition to a collection id ArangoDB will now also log the
  name of a collection for each replication event.

  The replication applier will now look for the collection name attribute in logged
  events preferably.

* added database selection to arango-dfdb

* provide foxx-manager, arangodump, and arangorestore in Windows build

* ArangoDB 1.4 will refuse to start if option `--javascript.app-path` is not set.

* added startup option `--server.allow-method-override`

  This option can be set to allow overriding the HTTP request method in a request using
  one of the following custom headers:

  - x-http-method-override
  - x-http-method
  - x-method-override

  This allows bypassing proxies and tools that would otherwise just let certain types of
  requests pass. Enabling this option may impose a security risk, so it should only be
  used in very controlled environments.

  The default value for this option is `false` (no method overriding allowed).

* added "details" URL parameter for bulk import API

  Setting the `details` URL parameter to `true` in a call to POST `/_api/import` will make
  the import return details about non-imported documents in the `details` attribute. If
  `details` is `false` or omitted, no `details` attribute will be present in the response.
  This is the same behavior that previous ArangoDB versions exposed.

* added "complete" option for bulk import API

  Setting the `complete` URL parameter to `true` in a call to POST `/_api/import` will make
  the import completely fail if at least one of documents cannot be imported successfully.

  It defaults to `false`, which will make ArangoDB continue importing the other documents
  from the import even if some documents cannot be imported. This is the same behavior that
  previous ArangoDB versions exposed.

* added missing swagger documentation for `/_api/log`

* calling `/_api/logs` (or `/_admin/logs`) is only permitted from the `_system` database now.

  Calling this API method for/from other database will result in an HTTP 400.

' ported fix from https://github.com/novus/nvd3/commit/0894152def263b8dee60192f75f66700cea532cc

  This prevents JavaScript errors from occurring in Chrome when in the admin interface,
  section "Dashboard".

* show current database name in web interface (bottom right corner)

* added missing documentation for /_api/import in swagger API docs

* allow specification of database name for replication sync command replication applier

  This allows syncing from a master database with a different name than the slave database.

* issue #601: Show DB in prompt

  arangosh now displays the database name as part of the prompt by default.

  Can change the prompt by using the `--prompt` option, e.g.

      > arangosh --prompt "my db is named \"%d\"> "


v1.4.0-beta1 (2013-10-01)
-------------------------

* make the Foxx manager use per-database app directories

  Each database now has its own subdirectory for Foxx applications. Each database
  can thus use different Foxx applications if required. A Foxx app for a specific
  database resides in `<app-path>/databases/<database-name>/<app-name>`.

  System apps are shared between all databases. They reside in `<app-path>/system/<app-name>`.

* only trigger an engine reset in development mode for URLs starting with `/dev/`

  This prevents ArangoDB from reloading all Foxx applications when it is not
  actually necessary.

* changed error code from 10 (bad parameter) to 1232 (invalid key generator) for
  errors that are due to an invalid key generator specification when creating a new
  collection

* automatic detection of content-type / mime-type for Foxx assets based on filenames,
  added possibility to override auto detection

* added endpoint management API at `/_api/endpoint`

* changed HTTP return code of PUT `/_api/cursor` from 400 to 404 in case a
  non-existing cursor is referred to

* issue #360: added support for asynchronous requests

  Incoming HTTP requests with the headers `x-arango-async: true` or
  `x-arango-async: store` will be answered by the server instantly with a generic
  HTTP 202 (Accepted) response.

  The actual requests will be queued and processed by the server asynchronously,
  allowing the client to continue sending other requests without waiting for the
  server to process the actually requested operation.

  The exact point in time when a queued request is executed is undefined. If an
  error occurs during execution of an asynchronous request, the client will not
  be notified by the server.

  The maximum size of the asynchronous task queue can be controlled using the new
  option `--scheduler.maximal-queue-size`. If the queue contains this many number of
  tasks and a new asynchronous request comes in, the server will reject it with an
  HTTP 500 (internal server error) response.

  Results of incoming requests marked with header `x-arango-async: true` will be
  discarded by the server immediately. Clients have no way of accessing the result
  of such asynchronously executed request. This is just _fire and forget_.

  To later retrieve the result of an asynchronously executed request, clients can
  mark a request with the header `x-arango-async: keep`. This makes the server
  store the result of the request in memory until explicitly fetched by a client
  via the `/_api/job` API. The `/_api/job` API also provides methods for basic
  inspection of which pending or already finished requests there are on the server,
  plus ways for garbage collecting unneeded results.

* Added new option `--scheduler.maximal-queue-size`.

* issue #590: Manifest Lint

* added data dump and restore tools, arangodump and arangorestore.

  arangodump can be used to create a logical dump of an ArangoDB database, or
  just dedicated collections. It can be used to dump both a collection's structure
  (properties and indexes) and data (documents).

  arangorestore can be used to restore data from a dump created with arangodump.
  arangorestore currently does not re-create any indexes, and doesn't yet handle
  referenced documents in edges properly when doing just partial restores.
  This will be fixed until 1.4 stable.

* introduced `--server.database` option for arangosh, arangoimp, and arangob.

  The option allows these client tools to use a certain database for their actions.
  In arangosh, the current database can be switched at any time using the command

      db._useDatabase(<name>);

  When no database is specified, all client tools will assume they should use the
  default database `_system`. This is done for downwards-compatibility reasons.

* added basic multi database support (alpha)

  New databases can be created using the REST API POST `/_api/database` and the
  shell command `db._createDatabase(<name>)`.

  The default database in ArangoDB is called `_system`. This database is always
  present and cannot be deleted by the user. When an older version of ArangoDB is
  upgraded to 1.4, the previously only database will automatically become the
  `_system` database.

  New databases can be created with the above commands, and can be deleted with the
  REST API DELETE `/_api/database/<name>` or the shell command `db._dropDatabase(<name>);`.

  Deleting databases is still unstable in ArangoDB 1.4 alpha and might crash the
  server. This will be fixed until 1.4 stable.

  To access a specific database via the HTTP REST API, the `/_db/<name>/` prefix
  can be used in all URLs. ArangoDB will check if an incoming request starts with
  this prefix, and will automatically pick the database name from it. If the prefix
  is not there, ArangoDB will assume the request is made for the default database
  (`_system`). This is done for downwards-compatibility reasons.

  That means, the following URL pathnames are logically identical:

      /_api/document/mycollection/1234
      /_db/_system/document/mycollection/1234

  To access a different database (e.g. `test`), the URL pathname would look like this:

      /_db/test/document/mycollection/1234

  New databases can also be created and existing databases can only be dropped from
  within the default database (`_system`). It is not possible to drop the `_system`
  database itself.

  Cross-database operations are unintended and unsupported. The intention of the
  multi-database feature is to have the possibility to have a few databases managed
  by ArangoDB in parallel, but to only access one database at a time from a connection
  or a request.

  When accessing the web interface via the URL pathname `/_admin/html/` or `/_admin/aardvark`,
  the web interface for the default database (`_system`) will be displayed.
  To access the web interface for a different database, the database name can be
  put into the URLs as a prefix, e.g. `/_db/test/_admin/html` or
  `/_db/test/_admin/aardvark`.

  All internal request handlers and also all user-defined request handlers and actions
  (including Foxx) will only get to see the unprefixed URL pathnames (i.e. excluding
  any database name prefix). This is to ensure downwards-compatibility.

  To access the name of the requested database from any action (including Foxx), use
  use `req.database`.

  For example, when calling the URL `/myapp/myaction`, the content of `req.database`
  will be `_system` (the default database because no database got specified) and the
  content of `req.url` will be `/myapp/myaction`.

  When calling the URL `/_db/test/myapp/myaction`, the content of `req.database` will be
  `test`, and the content of `req.url` will still be `/myapp/myaction`.

* Foxx now excludes files starting with . (dot) when bundling assets

  This mitigates problems with editor swap files etc.

* made the web interface a Foxx application

  This change caused the files for the web interface to be moved from `html/admin` to
  `js/apps/aardvark` in the file system.

  The base URL for the admin interface changed from `_admin/html/index.html` to
  `_admin/aardvark/index.html`.

  The "old" redirection to `_admin/html/index.html` will now produce a 404 error.

  When starting ArangoDB with the `--upgrade` option, this will automatically be remedied
  by putting in a redirection from `/` to `/_admin/aardvark/index.html`, and from
  `/_admin/html/index.html` to `/_admin/aardvark/index.html`.

  This also obsoletes the following configuration (command-line) options:
  - `--server.admin-directory`
  - `--server.disable-admin-interface`

  when using these now obsolete options when the server is started, no error is produced
  for downwards-compatibility.

* changed User-Agent value sent by arangoimp, arangosh, and arangod from "VOC-Agent" to
  "ArangoDB"

* changed journal file creation behavior as follows:

  Previously, a journal file for a collection was always created when a collection was
  created. When a journal filled up and became full, the current journal was made a
  datafile, and a new (empty) journal was created automatically. There weren't many
  intended situations when a collection did not have at least one journal.

  This is changed now as follows:
  - when a collection is created, no journal file will be created automatically
  - when there is a write into a collection without a journal, the journal will be
    created lazily
  - when there is a write into a collection with a full journal, a new journal will
    be created automatically

  From the end user perspective, nothing should have changed, except that there is now
  less disk usage for empty collections. Disk usage of infrequently updated collections
  might also be reduced significantly by running the `rotate()` method of a collection,
  and not writing into a collection subsequently.

* added method `collection.rotate()`

  This allows premature rotation of a collection's current journal file into a (read-only)
  datafile. The purpose of using `rotate()` is to prematurely allow compaction (which is
  performed on datafiles only) on data, even if the journal was not filled up completely.

  Using `rotate()` may make sense in the following scenario:

      c = db._create("test");
      for (i = 0; i < 1000; ++i) {
        c.save(...); // insert lots of data here
      }

      ...
      c.truncate(); // collection is now empty
      // only data in datafiles will be compacted by following compaction runs
      // all data in the current journal would not be compacted

      // calling rotate will make the current journal a datafile, and thus make it
      // eligible for compaction
      c.rotate();

  Using `rotate()` may also be useful when data in a collection is known to not change
  in the immediate future. After having completed all write operations on a collection,
  performing a `rotate()` will reduce the size of the current journal to the actually
  required size (remember that journals are pre-allocated with a specific size) before
  making the journal a datafile. Thus `rotate()` may cause disk space savings, even if
  the datafiles does not qualify for compaction after rotation.

  Note: rotating the journal is asynchronous, so that the actual rotation may be executed
  after `rotate()` returns to the caller.

* changed compaction to merge small datafiles together (up to 3 datafiles are merged in
  a compaction run)

  In the regular case, this should leave less small datafiles stay around on disk and allow
  using less file descriptors in total.

* added AQL MINUS function

* added AQL UNION_DISTINCT function (more efficient than combination of `UNIQUE(UNION())`)

* updated mruby to 2013-08-22

* issue #587: Add db._create() in help for startup arangosh

* issue #586: Share a link on installation instructions in the User Manual

* issue #585: Bison 2.4 missing on Mac for custom build

* issue #584: Web interface images broken in devel

* issue #583: Small documentation update

* issue #581: Parameter binding for attributes

* issue #580: Small improvements (by @guidoreina)

* issue #577: Missing documentation for collection figures in implementor manual

* issue #576: Get disk usage for collections and graphs

  This extends the result of the REST API for /_api/collection/figures with
  the attributes `compactors.count`, `compactors.fileSize`, `shapefiles.count`,
  and `shapefiles.fileSize`.

* issue #575: installing devel version on mac (low prio)

* issue #574: Documentation (POST /_admin/routing/reload)

* issue #558: HTTP cursors, allow count to ignore LIMIT


v1.4.0-alpha1 (2013-08-02)
--------------------------

* added replication. check online manual for details.

* added server startup options `--server.disable-replication-logger` and
  `--server.disable-replication-applier`

* removed action deployment tool, this now handled with Foxx and its manager or
  by kaerus node utility

* fixed a server crash when using byExample / firstExample inside a transaction
  and the collection contained a usable hash/skiplist index for the example

* defineHttp now only expects a single context

* added collection detail dialog (web interface)

  Shows collection properties, figures (datafiles, journals, attributes, etc.)
  and indexes.

* added documents filter (web interface)

  Allows searching for documents based on attribute values. One or many filter
  conditions can be defined, using comparison operators such as '==', '<=', etc.

* improved AQL editor (web interface)

  Editor supports keyboard shortcuts (Submit, Undo, Redo, Select).
  Editor allows saving and reusing of user-defined queries.
  Added example queries to AQL editor.
  Added comment button.

* added document import (web interface)

  Allows upload of JSON-data from files. Files must have an extension of .json.

* added dashboard (web interface)

  Shows the status of replication and multiple system charts, e.g.
  Virtual Memory Size, Request Time, HTTP Connections etc.

* added API method `/_api/graph` to query all graphs with all properties.

* added example queries in web interface AQL editor

* added arango.reconnect(<host>) method for arangosh to dynamically switch server or
  user name

* added AQL range operator `..`

  The `..` operator can be used to easily iterate over a sequence of numeric
  values. It will produce a list of values in the defined range, with both bounding
  values included.

  Example:

      2010..2013

  will produce the following result:

      [ 2010, 2011, 2012, 2013 ]

* added AQL RANGE function

* added collection.first(count) and collection.last(count) document access functions

  These functions allow accessing the first or last n documents in a collection. The order
  is determined by document insertion/update time.

* added AQL INTERSECTION function

* INCOMPATIBLE CHANGE: changed AQL user function namespace resolution operator from `:` to `::`

  AQL user-defined functions were introduced in ArangoDB 1.3, and the namespace resolution
  operator for them was the single colon (`:`). A function call looked like this:

      RETURN mygroup:myfunc()

  The single colon caused an ambiguity in the AQL grammar, making it indistinguishable from
  named attributes or the ternary operator in some cases, e.g.

      { mygroup:myfunc ? mygroup:myfunc }

  The change of the namespace resolution operator from `:` to `::` fixes this ambiguity.

  Existing user functions in the database will be automatically fixed when starting ArangoDB
  1.4 with the `--upgrade` option. However, queries using user-defined functions need to be
  adjusted on the client side to use the new operator.

* allow multiple AQL LET declarations separated by comma, e.g.
  LET a = 1, b = 2, c = 3

* more useful AQL error messages

  The error position (line/column) is more clearly indicated for parse errors.
  Additionally, if a query references a collection that cannot be found, the error
  message will give a hint on the collection name

* changed return value for AQL `DOCUMENT` function in case document is not found

  Previously, when the AQL `DOCUMENT` function was called with the id of a document and
  the document could not be found, it returned `undefined`. This value is not part of the
  JSON type system and this has caused some problems.
  Starting with ArangoDB 1.4, the `DOCUMENT` function will return `null` if the document
  looked for cannot be found.

  In case the function is called with a list of documents, it will continue to return all
  found documents, and will not return `null` for non-found documents. This has not changed.

* added single line comments for AQL

  Single line comments can be started with a double forward slash: `//`.
  They end at the end of the line, or the end of the query string, whichever is first.

* fixed documentation issues #567, #568, #571.

* added collection.checksum(<withData>) method to calculate CRC checksums for
  collections

  This can be used to
  - check if data in a collection has changed
  - compare the contents of two collections on different ArangoDB instances

* issue #565: add description line to aal.listAvailable()

* fixed several out-of-memory situations when double freeing or invalid memory
  accesses could happen

* less msyncing during the creation of collections

  This is achieved by not syncing the initial (standard) markers in shapes collections.
  After all standard markers are written, the shapes collection will get synced.

* renamed command-line option `--log.filter` to `--log.source-filter` to avoid
  misunderstandings

* introduced new command-line option `--log.content-filter` to optionally restrict
  logging to just specific log messages (containing the filter string, case-sensitive).

  For example, to filter on just log entries which contain `ArangoDB`, use:

      --log.content-filter "ArangoDB"

* added optional command-line option `--log.requests-file` to log incoming HTTP
  requests to a file.

  When used, all HTTP requests will be logged to the specified file, containing the
  client IP address, HTTP method, requests URL, HTTP response code, and size of the
  response body.

* added a signal handler for SIGUSR1 signal:

  when ArangoDB receives this signal, it will respond all further incoming requests
  with an HTTP 503 (Service Unavailable) error. This will be the case until another
  SIGUSR1 signal is caught. This will make ArangoDB start serving requests regularly
  again. Note: this is not implemented on Windows.

* limited maximum request URI length to 16384 bytes:

  Incoming requests with longer request URIs will be responded to with an HTTP
  414 (Request-URI Too Long) error.

* require version 1.0 or 1.1 in HTTP version signature of requests sent by clients:

  Clients sending requests with a non-HTTP 1.0 or non-HTTP 1.1 version number will
  be served with an HTTP 505 (HTTP Version Not Supported) error.

* updated manual on indexes:

  using system attributes such as `_id`, `_key`, `_from`, `_to`, `_rev` in indexes is
  disallowed and will be rejected by the server. This was the case since ArangoDB 1.3,
  but was not properly documented.

* issue #563: can aal become a default object?

  aal is now a prefab object in arangosh

* prevent certain system collections from being renamed, dropped, or even unloaded.

  Which restrictions there are for which system collections may vary from release to
  release, but users should in general not try to modify system collections directly
  anyway.

  Note: there are no such restrictions for user-created collections.

* issue #559: added Foxx documentation to user manual

* added server startup option `--server.authenticate-system-only`. This option can be
  used to restrict the need for HTTP authentication to internal functionality and APIs,
  such as `/_api/*` and `/_admin/*`.
  Setting this option to `true` will thus force authentication for the ArangoDB APIs
  and the web interface, but allow unauthenticated requests for other URLs (including
  user defined actions and Foxx applications).
  The default value of this option is `false`, meaning that if authentication is turned
  on, authentication is still required for *all* incoming requests. Only by setting the
  option to `true` this restriction is lifted and authentication becomes required for
  URLs starting with `/_` only.

  Please note that authentication still needs to be enabled regularly by setting the
  `--server.disable-authentication` parameter to `false`. Otherwise no authentication
  will be required for any URLs as before.

* protect collections against unloading when there are still document barriers around.

* extended cap constraints to optionally limit the active data size in a collection to
  a specific number of bytes.

  The arguments for creating a cap constraint are now:
  `collection.ensureCapConstraint(<count>, <byteSize>);`

  It is supported to specify just a count as in ArangoDB 1.3 and before, to specify
  just a fileSize, or both. The first met constraint will trigger the automated
  document removal.

* added `db._exists(doc)` and `collection.exists(doc)` for easy document existence checks

* added API `/_api/current-database` to retrieve information about the database the
  client is currently connected to (note: the API `/_api/current-database` has been
  removed in the meantime. The functionality is accessible via `/_api/database/current`
  now).

* ensure a proper order of tick values in datafiles/journals/compactors.
  any new files written will have the _tick values of their markers in order. for
  older files, there are edge cases at the beginning and end of the datafiles when
  _tick values are not properly in order.

* prevent caching of static pages in PathHandler.
  whenever a static page is requested that is served by the general PathHandler, the
  server will respond to HTTP GET requests with a "Cache-Control: max-age=86400" header.

* added "doCompact" attribute when creating collections and to collection.properties().
  The attribute controls whether collection datafiles are compacted.

* changed the HTTP return code from 400 to 404 for some cases when there is a referral
  to a non-existing collection or document.

* introduced error code 1909 `too many iterations` that is thrown when graph traversals
  hit the `maxIterations` threshold.

* optionally limit traversals to a certain number of iterations
  the limitation can be achieved via the traversal API by setting the `maxIterations`
  attribute, and also via the AQL `TRAVERSAL` and `TRAVERSAL_TREE` functions by setting
  the same attribute. If traversals are not limited by the end user, a server-defined
  limit for `maxIterations` may be used to prevent server-side traversals from running
  endlessly.

* added graph traversal API at `/_api/traversal`

* added "API" link in web interface, pointing to REST API generated with Swagger

* moved "About" link in web interface into "links" menu

* allow incremental access to the documents in a collection from out of AQL
  this allows reading documents from a collection chunks when a full collection scan
  is required. memory usage might be must lower in this case and queries might finish
  earlier if there is an additional LIMIT statement

* changed AQL COLLECT to use a stable sort, so any previous SORT order is preserved

* issue #547: Javascript error in the web interface

* issue #550: Make AQL graph functions support key in addition to id

* issue #526: Unable to escape when an errorneous command is entered into the js shell

* issue #523: Graph and vertex methods for the javascript api

* issue #517: Foxx: Route parameters with capital letters fail

* issue #512: Binded Parameters for LIMIT


v1.3.3 (2013-08-01)
-------------------

* issue #570: updateFishbowl() fails once

* updated and fixed generated examples

* issue #559: added Foxx documentation to user manual

* added missing error reporting for errors that happened during import of edges


v1.3.2 (2013-06-21)
-------------------

* fixed memleak in internal.download()

* made the shape-collection journal size adaptive:
  if too big shapes come in, a shape journal will be created with a big-enough size
  automatically. the maximum size of a shape journal is still restricted, but to a
  very big value that should never be reached in practice.

* fixed a segfault that occurred when inserting documents with a shape size bigger
  than the default shape journal size (2MB)

* fixed a locking issue in collection.truncate()

* fixed value overflow in accumulated filesizes reported by collection.figures()

* issue #545: AQL FILTER unnecessary (?) loop

* issue #549: wrong return code with --daemon


v1.3.1 (2013-05-24)
-------------------

* removed currently unused _ids collection

* fixed usage of --temp-path in aranogd and arangosh

* issue #540: suppress return of temporary internal variables in AQL

* issue #530: ReferenceError: ArangoError is not a constructor

* issue #535: Problem with AQL user functions javascript API

* set --javascript.app-path for test execution to prevent startup error

* issue #532: Graph _edgesCache returns invalid data?

* issue #531: Arangod errors

* issue #529: Really weird transaction issue

* fixed usage of --temp-path in aranogd and arangosh


v1.3.0 (2013-05-10)
-------------------

* fixed problem on restart ("datafile-xxx is not sealed") when server was killed
  during a compaction run

* fixed leak when using cursors with very small batchSize

* issue #508: `unregistergroup` function not mentioned in http interface docs

* issue #507: GET /_api/aqlfunction returns code inside parentheses

* fixed issue #489: Bug in aal.install

* fixed issue 505: statistics not populated on MacOS


v1.3.0-rc1 (2013-04-24)
-----------------------

* updated documentation for 1.3.0

* added node modules and npm packages

* changed compaction to only compact datafiles with more at least 10% of dead
  documents (byte size-wise)

* issue #498: fixed reload of authentication info when using
  `require("org/arangodb/users").reload()`

* issue #495: Passing an empty array to create a document results in a
  "phantom" document

* added more precision for requests statistics figures

* added "sum" attribute for individual statistics results in statistics API
  at /_admin/statistics

* made "limit" an optional parameter in AQL function NEAR().
  limit can now be either omitted completely, or set to 0. If so, an internal
  default value (currently 100) will be applied for the limit.

* issue #481

* added "attributes.count" to output of `collection.figures()`
  this also affects the REST API /_api/collection/<name>/figures

* added IndexedPropertyGetter for ShapedJson objects

* added API for user-defined AQL functions

* issue #475: A better error message for deleting a non-existent graph

* issue #474: Web interface problems with the JS Shell

* added missing documentation for AQL UNION function

* added transaction support.
  This provides ACID transactions for ArangoDB. Transactions can be invoked
  using the `db._executeTransaction()` function, or the `/_api/transaction`
  REST API.

* switched to semantic versioning (at least for alpha & alpha naming)

* added saveOrReplace() for server-side JS

v1.3.alpha1 (2013-04-05)
------------------------

* cleanup of Module, Package, ArangoApp and modules "internal", "fs", "console"

* use Error instead of string in throw to allow stack-trace

* issue #454: error while creation of Collection

* make `collection.count()` not recalculate the number of documents on the fly, but
  use some internal document counters.

* issue #457: invalid string value in web interface

* make datafile id (datafile->_fid) identical to the numeric part of the filename.
  E.g. the datafile `journal-123456.db` will now have a datafile marker with the same
  fid (i.e. `123456`) instead of a different value. This change will only affect
  datafiles that are created with 1.3 and not any older files.
  The intention behind this change is to make datafile debugging easier.

* consistently discard document attributes with reserved names (system attributes)
  but without any known meaning, for example `_test`, `_foo`, ...

  Previously, these attributes were saved with the document regularly in some cases,
  but were discarded in other cases.
  Now these attributes are discarded consistently. "Real" system attributes such as
  `_key`, `_from`, `_to` are not affected and will work as before.

  Additionally, attributes with an empty name (``) are discarded when documents are
  saved.

  Though using reserved or empty attribute names in documents was not really and
  consistently supported in previous versions of ArangoDB, this change might cause
  an incompatibility for clients that rely on this feature.

* added server startup flag `--database.force-sync-properties` to force syncing of
  collection properties on collection creation, deletion and on property update.
  The default value is true to mimic the behavior of previous versions of ArangoDB.
  If set to false, collection properties are written to disk but no call to sync()
  is made.

* added detailed output of server version and components for REST APIs
  `/_admin/version` and `/_api/version`. To retrieve this extended information,
  call the REST APIs with URL parameter `details=true`.

* issue #443: For git-based builds include commit hash in version

* adjust startup log output to be more compact, less verbose

* set the required minimum number of file descriptors to 256.
  On server start, this number is enforced on systems that have rlimit. If the limit
  cannot be enforced, starting the server will fail.
  Note: 256 is considered to be the absolute minimum value. Depending on the use case
  for ArangoDB, a much higher number of file descriptors should be used.

  To avoid checking & potentially changing the number of maximum open files, use the
  startup option `--server.descriptors-minimum 0`

* fixed shapedjson to json conversion for special numeric values (NaN, +inf, -inf).
  Before, "NaN", "inf", or "-inf" were written into the JSONified output, but these
  values are not allowed in JSON. Now, "null" is written to the JSONified output as
  required.

* added AQL functions VARIANCE_POPULATION(), VARIANCE_SAMPLE(), STDDEV_POPULATION(),
  STDDEV_SAMPLE(), AVERAGE(), MEDIAN() to calculate statistical values for lists

* added AQL SQRT() function

* added AQL TRIM(), LEFT() and RIGHT() string functions

* fixed issue #436: GET /_api/document on edge

* make AQL REVERSE() and LENGTH() functions work on strings, too

* disabled DOT generation in `make doxygen`. this speeds up docs generation

* renamed startup option `--dispatcher.report-intervall` to `--dispatcher.report-interval`

* renamed startup option `--scheduler.report-intervall` to `--scheduler.report-interval`

* slightly changed output of REST API method /_admin/log.
  Previously, the log messages returned also contained the date and log level, now
  they will only contain the log message, and no date and log level information.
  This information can be re-created by API users from the `timestamp` and `level`
  attributes of the result.

* removed configure option `--enable-zone-debug`
  memory zone debugging is now automatically turned on when compiling with ArangoDB
  `--enable-maintainer-mode`

* removed configure option `--enable-arangob`
  arangob is now always included in the build


v1.2.3 (XXXX-XX-XX)
-------------------

* added optional parameter `edgexamples` for AQL function EDGES() and NEIGHBORS()

* added AQL function NEIGHBORS()

* added freebsd support

* fixed firstExample() query with `_id` and `_key` attributes

* issue triAGENS/ArangoDB-PHP#55: AQL optimizer may have mis-optimized duplicate
  filter statements with limit


v1.2.2 (2013-03-26)
-------------------

* fixed save of objects with common sub-objects

* issue #459: fulltext internal memory allocation didn't scale well
  This fix improves loading times for collections with fulltext indexes that have
  lots of equal words indexed.

* issue #212: auto-increment support

  The feature can be used by creating a collection with the extra `keyOptions`
  attribute as follows:

      db._create("mycollection", { keyOptions: { type: "autoincrement", offset: 1, increment: 10, allowUserKeys: true } });

  The `type` attribute will make sure the keys will be auto-generated if no
  `_key` attribute is specified for a document.

  The `allowUserKeys` attribute determines whether users might still supply own
  `_key` values with documents or if this is considered an error.

  The `increment` value determines the actual increment value, whereas the `offset`
  value can be used to seed to value sequence with a specific starting value.
  This will be useful later in a multi-master setup, when multiple servers can use
  different auto-increment seed values and thus generate non-conflicting auto-increment values.

  The default values currently are:

  - `allowUserKeys`: `true`
  - `offset`: `0`
  - `increment`: `1`

  The only other available key generator type currently is `traditional`.
  The `traditional` key generator will auto-generate keys in a fashion as ArangoDB
  always did (some increasing integer value, with a more or less unpredictable
  increment value).

  Note that for the `traditional` key generator there is only the option to disallow
  user-supplied keys and give the server the sole responsibility for key generation.
  This can be achieved by setting the `allowUserKeys` property to `false`.

  This change also introduces the following errors that API implementors may want to check
  the return values for:

  - 1222: `document key unexpected`: will be raised when a document is created with
    a `_key` attribute, but the underlying collection was set up with the `keyOptions`
    attribute `allowUserKeys: false`.

  - 1225: `out of keys`: will be raised when the auto-increment key generator runs
    out of keys. This may happen when the next key to be generated is 2^64 or higher.
    In practice, this will only happen if the values for `increment` or `offset` are
    not set appropriately, or if users are allowed to supply own keys, those keys
    are near the 2^64 threshold, and later the auto-increment feature kicks in and
    generates keys that cross that threshold.

    In practice it should not occur with proper configuration and proper usage of the
    collections.

  This change may also affect the following REST APIs:
  - POST `/_api/collection`: the server does now accept the optional `keyOptions`
    attribute in the second parameter
  - GET `/_api/collection/properties`: will return the `keyOptions` attribute as part
    of the collection's properties. The previous optional attribute `createOptions`
    is now gone.

* fixed `ArangoStatement.explain()` method with bind variables

* fixed misleading "cursor not found" error message in arangosh that occurred when
  `count()` was called for client-side cursors

* fixed handling of empty attribute names, which may have crashed the server under
  certain circumstances before

* fixed usage of invalid pointer in error message output when index description could
  not be opened


v1.2.1 (2013-03-14)
-------------------

* issue #444: please darken light color in arangosh

* issue #442: pls update post install info on osx

* fixed conversion of special double values (NaN, -inf, +inf) when converting from
  shapedjson to JSON

* fixed compaction of markers (location of _key was not updated correctly in memory,
  leading to _keys pointing to undefined memory after datafile rotation)

* fixed edge index key pointers to use document master pointer plus offset instead
  of direct _key address

* fixed case when server could not create any more journal or compactor files.
  Previously a wrong status code may have been returned, and not being able to create
  a new compactor file may have led to an infinite loop with error message
  "could not create compactor".

* fixed value truncation for numeric filename parts when renaming datafiles/journals


v1.2.0 (2013-03-01)
-------------------

* by default statistics are now switch off; in order to enable comment out
  the "disable-statistics = yes" line in "arangod.conf"

* fixed issue #435: csv parser skips data at buffer border

* added server startup option `--server.disable-statistics` to turn off statistics
  gathering without recompilation of ArangoDB.
  This partly addresses issue #432.

* fixed dropping of indexes without collection name, e.g.
  `db.xxx.dropIndex("123456");`
  Dropping an index like this failed with an assertion error.

* fixed issue #426: arangoimp should be able to import edges into edge collections

* fixed issue #425: In case of conflict ArangoDB returns HTTP 400 Bad request
  (with 1207 Error) instead of HTTP 409 Conflict

* fixed too greedy token consumption in AQL for negative values:
  e.g. in the statement `RETURN { a: 1 -2 }` the minus token was consumed as part
  of the value `-2`, and not interpreted as the binary arithmetic operator


v1.2.beta3 (2013-02-22)
-----------------------

* issue #427: ArangoDB Importer Manual has no navigation links (previous|home|next)

* issue #319: Documentation missing for Emergency console and incomplete for datafile debugger.

* issue #370: add documentation for reloadRouting and flushServerModules

* issue #393: added REST API for user management at /_api/user

* issue #393, #128: added simple cryptographic functions for user actions in module "crypto":
  * require("org/arangodb/crypto").md5()
  * require("org/arangodb/crypto").sha256()
  * require("org/arangodb/crypto").rand()

* added replaceByExample() Javascript and REST API method

* added updateByExample() Javascript and REST API method

* added optional "limit" parameter for removeByExample() Javascript and REST API method

* fixed issue #413

* updated bundled V8 version from 3.9.4 to 3.16.14.1
  Note: the Windows version used a more recent version (3.14.0.1) and was not updated.

* fixed issue #404: keep original request url in request object


v1.2.beta2 (2013-02-15)
-----------------------

* fixed issue #405: 1.2 compile warnings

* fixed issue #333: [debian] Group "arangodb" is not used when starting vie init.d script

* added optional parameter 'excludeSystem' to GET /_api/collection
  This parameter can be used to disable returning system collections in the list
  of all collections.

* added AQL functions KEEP() and UNSET()

* fixed issue #348: "HTTP Interface for Administration and Monitoring"
  documentation errors.

* fix stringification of specific positive int64 values. Stringification of int64
  values with the upper 32 bits cleared and the 33rd bit set were broken.

* issue #395:  Collection properties() function should return 'isSystem' for
  Javascript and REST API

* make server stop after upgrade procedure when invoked with `--upgrade option`.
  When started with the `--upgrade` option, the server will perfom
  the upgrade, and then exit with a status code indicating the result of the
  upgrade (0 = success, 1 = failure). To start the server regularly in either
  daemon or console mode, the `--upgrade` option must not be specified.
  This change was introduced to allow init.d scripts check the result of
  the upgrade procedure, even in case an upgrade was successful.
  this was introduced as part of issue #391.

* added AQL function EDGES()

* added more crash-protection when reading corrupted collections at startup

* added documentation for AQL function CONTAINS()

* added AQL function LIKE()

* replaced redundant error return code 1520 (Unable to open collection) with error code
  1203 (Collection not found). These error codes have the same meanings, but one of
  them was returned from AQL queries only, the other got thrown by other parts of
  ArangoDB. Now, error 1203 (Collection not found) is used in AQL too in case a
  non-existing collection is used.

v1.2.beta1 (2013-02-01)
-----------------------

* fixed issue #382: [Documentation error] Maschine... should be Machine...

* unified history file locations for arangod, arangosh, and arangoirb.
  - The readline history for arangod (emergency console) is now stored in file
    $HOME/.arangod. It was stored in $HOME/.arango before.
  - The readline history for arangosh is still stored in $HOME/.arangosh.
  - The readline history for arangoirb is now stored in $HOME/.arangoirb. It was
    stored in $HOME/.arango-mrb before.

* fixed issue #381: _users user should have a unique constraint

* allow negative list indexes in AQL to access elements from the end of a list,
  e.g. ```RETURN values[-1]``` will return the last element of the `values` list.

* collection ids, index ids, cursor ids, and document revision ids created and
  returned by ArangoDB are now returned as strings with numeric content inside.
  This is done to prevent some value overrun/truncation in any part of the
  complete client/server workflow.
  In ArangoDB 1.1 and before, these values were previously returned as
  (potentially very big) integer values. This may cause problems (clipping, overrun,
  precision loss) for clients that do not support big integers natively and store
  such values in IEEE754 doubles internally. This type loses precision after about
  52 bits and is thus not safe to hold an id.
  Javascript and 32 bit-PHP are examples for clients that may cause such problems.
  Therefore, ids are now returned by ArangoDB as strings, with the string
  content being the integer value as before.

  Example for documents ("_rev" attribute):
  - Document returned by ArangoDB 1.1: { "_rev": 1234, ... }
  - Document returned by ArangoDB 1.2: { "_rev": "1234", ... }

  Example for collections ("id" attribute / "_id" property):
  - Collection returned by ArangoDB 1.1: { "id": 9327643, "name": "test", ... }
  - Collection returned by ArangoDB 1.2: { "id": "9327643", "name": "test", ... }

  Example for cursors ("id" attribute):
  - Collection returned by ArangoDB 1.1: { "id": 11734292, "hasMore": true, ... }
  - Collection returned by ArangoDB 1.2: { "id": "11734292", "hasMore": true, ... }

* global variables are not automatically available anymore when starting the
  arangod Javascript emergency console (i.e. ```arangod --console```).

  Especially, the variables `db`, `edges`, and `internal` are not available
  anymore. `db` and `internal` can be made available in 1.2 by
  ```var db = require("org/arangodb").db;``` and
  ```var internal = require("internal");```, respectively.
  The reason for this change is to get rid of global variables in the server
  because this will allow more specific inclusion of functionality.

  For convenience, the global variable `db` is still available by default in
  arangosh. The global variable `edges`, which since ArangoDB 1.1 was kind of
  a redundant wrapper of `db`, has been removed in 1.2 completely.
  Please use `db` instead, and if creating an edge collection, use the explicit
  ```db._createEdgeCollection()``` command.

* issue #374: prevent endless redirects when calling admin interface with
  unexpected URLs

* issue #373: TRAVERSAL() `trackPaths` option does not work. Instead `paths` does work

* issue #358: added support for CORS

* honor optional waitForSync property for document removal, replace, update, and
  save operations in arangosh. The waitForSync parameter for these operations
  was previously honored by the REST API and on the server-side, but not when
  the waitForSync parameter was specified for a document operation in arangosh.

* calls to db.collection.figures() and /_api/collection/<collection>/figures now
  additionally return the number of shapes used in the collection in the
  extra attribute "shapes.count"

* added AQL TRAVERSAL_TREE() function to return a hierarchical result from a traversal

* added AQL TRAVERSAL() function to return the results from a traversal

* added AQL function ATTRIBUTES() to return the attribute names of a document

* removed internal server-side AQL functions from global scope.

  Now the AQL internal functions can only be accessed via the exports of the
  ahuacatl module, which can be included via ```require("org/arangodb/ahuacatl")```.
  It shouldn't be necessary for clients to access this module at all, but
  internal code may use this module.

  The previously global AQL-related server-side functions were moved to the
  internal namespace. This produced the following function name changes on
  the server:

     old name              new name
     ------------------------------------------------------
     AHUACATL_RUN       => require("internal").AQL_QUERY
     AHUACATL_EXPLAIN   => require("internal").AQL_EXPLAIN
     AHUACATL_PARSE     => require("internal").AQL_PARSE

  Again, clients shouldn't have used these functions at all as there is the
  ArangoStatement object to execute AQL queries.

* fixed issue #366: Edges index returns strange description

* added AQL function MATCHES() to check a document against a list of examples

* added documentation and tests for db.collection.removeByExample

* added --progress option for arangoimp. This will show the percentage of the input
  file that has been processed by arangoimp while the import is still running. It can
  be used as a rough indicator of progress for the entire import.

* make the server log documents that cannot be imported via /_api/import into the
  logfile using the warning log level. This may help finding illegal documents in big
  import runs.

* check on server startup whether the database directory and all collection directories
  are writable. if not, the server startup will be aborted. this prevents serious
  problems with collections being non-writable and this being detected at some pointer
  after the server has been started

* allow the following AQL constructs: FUNC(...)[...], FUNC(...).attribute

* fixed issue #361: Bug in Admin Interface. Header disappears when clicking new collection

* Added in-memory only collections

  Added collection creation parameter "isVolatile":
  if set to true, the collection is created as an in-memory only collection,
  meaning that all document data of that collection will reside in memory only,
  and will not be stored permanently to disk.
  This means that all collection data will be lost when the collection is unloaded
  or the server is shut down.
  As this collection type does not have datafile disk overhead for the regular
  document operations, it may be faster than normal disk-backed collections. The
  actual performance gains strongly depend on the underlying OS, filesystem, and
  settings though.
  This collection type should be used for caches only and not for any sensible data
  that cannot be re-created otherwise.
  Some platforms, namely Windows, currently do not support this collection type.
  When creating an in-memory collection on such platform, an error message will be
  returned by ArangoDB telling the user the platform does not support it.

  Note: in-memory collections are an experimental feature. The feature might
  change drastically or even be removed altogether in a future version of ArangoDB.

* fixed issue #353: Please include "pretty print" in Emergency Console

* fixed issue #352: "pretty print" console.log
  This was achieved by adding the dump() function for the "internal" object

* reduced insertion time for edges index
  Inserting into the edges index now avoids costly comparisons in case of a hash
  collision, reducing the prefilling/loading timer for bigger edge collections

* added fulltext queries to AQL via FULLTEXT() function. This allows search
  fulltext indexes from an AQL query to find matching documents

* added fulltext index type. This index type allows indexing words and prefixes of
  words from a specific document attribute. The index can be queries using a
  SimpleQueryFull object, the HTTP REST API at /_api/simple/fulltext, or via AQL

* added collection.revision() method to determine whether a collection has changed.
  The revision method returns a revision string that can be used by client programs
  for equality/inequality comparisons. The value returned by the revision method
  should be treated by clients as an opaque string and clients should not try to
  figure out the sense of the revision id. This is still useful enough to check
  whether data in a collection has changed.

* issue #346: adaptively determine NUMBER_HEADERS_PER_BLOCK

* issue #338: arangosh cursor positioning problems

* issue #326: use limit optimization with filters

* issue #325: use index to avoid sorting

* issue #324: add limit optimization to AQL

* removed arango-password script and added Javascript functionality to add/delete
  users instead. The functionality is contained in module `users` and can be invoked
  as follows from arangosh and arangod:
  * require("users").save("name", "passwd");
  * require("users").replace("name", "newPasswd");
  * require("users").remove("name");
  * require("users").reload();
  These functions are intentionally not offered via the web interface.
  This also addresses issue #313

* changed print output in arangosh and the web interface for JSON objects.
  Previously, printing a JSON object in arangosh resulted in the attribute values
  being printed as proper JSON, but attribute names were printed unquoted and
  unescaped. This was fine for the purpose of arangosh, but lead to invalid
  JSON being produced. Now, arangosh will produce valid JSON that can be used
  to send it back to ArangoDB or use it with arangoimp etc.

* fixed issue #300: allow importing documents via the REST /_api/import API
  from a JSON list, too.
  So far, the API only supported importing from a format that had one JSON object
  on each line. This is sometimes inconvenient, e.g. when the result of an AQL
  query or any other list is to be imported. This list is a JSON list and does not
  necessary have a document per line if pretty-printed.
  arangoimp now supports the JSON list format, too. However, the format requires
  arangoimp and the server to read the entire dataset at once. If the dataset is
  too big (bigger than --max-upload-size) then the import will be rejected. Even if
  increased, the entire list must fit in memory on both the client and the server,
  and this may be more resource-intensive than importing individual lines in chunks.

* removed unused parameter --reuse-ids for arangoimp. This parameter did not have
  any effect in 1.2, was never publicly announced and did evil (TM) things.

* fixed issue #297 (partly): added whitespace between command line and
  command result in arangosh, added shell colors for better usability

* fixed issue #296: system collections not usable from AQL

* fixed issue #295: deadlock on shutdown

* fixed issue #293: AQL queries should exploit edges index

* fixed issue #292: use index when filtering on _key in AQL

* allow user-definable document keys
  users can now define their own document keys by using the _key attribute
  when creating new documents or edges. Once specified, the value of _key is
  immutable.
  The restrictions for user-defined key values are:
  * the key must be at most 254 bytes long
  * it must consist of the letters a-z (lower or upper case), the digits 0-9,
    the underscore (_) or dash (-) characters only
  * any other characters, especially multi-byte sequences, whitespace or
    punctuation characters cannot be used inside key values

  Specifying a document key is optional when creating new documents. If no
  document key is specified, ArangoDB will create a document key itself.
  There are no guarantees about the format and pattern of auto-generated document
  keys other than the above restrictions.
  Clients should therefore treat auto-generated document keys as opaque values.
  Keys can be used to look up and reference documents, e.g.:
  * saving a document: `db.users.save({ "_key": "fred", ... })`
  * looking up a document: `db.users.document("fred")`
  * referencing other documents: `edges.relations.save("users/fred", "users/john", ...)`

  This change is downwards-compatible to ArangoDB 1.1 because in ArangoDB 1.1
  users were not able to define their own keys. If the user does not supply a _key
  attribute when creating a document, ArangoDB 1.2 will still generate a key of
  its own as ArangoDB 1.1 did. However, all documents returned by ArangoDB 1.2 will
  include a _key attribute and clients should be able to handle that (e.g. by
  ignoring it if not needed). Documents returned will still include the _id attribute
  as in ArangoDB 1.1.

* require collection names everywhere where a collection id was allowed in
  ArangoDB 1.1 & 1.0
  This change requires clients to use a collection name in place of a collection id
  at all places the client deals with collections.
  Examples:
  * creating edges: the _from and _to attributes must now contain collection names instead
    of collection ids: `edges.relations.save("test/my-key1", "test/my-key2", ...)`
  * retrieving edges: the returned _from and _to attributes now will contain collection
    names instead of ids, too: _from: `test/fred` instead of `1234/3455`
  * looking up documents: db.users.document("fred") or db._document("users/fred")

  Collection names must be used in REST API calls instead of collection ids, too.
  This change is thus not completely downwards-compatible to ArangoDB 1.1. ArangoDB 1.1
  required users to use collection ids in many places instead of collection names.
  This was unintuitive and caused overhead in cases when just the collection name was
  known on client-side but not its id. This overhead can now be avoided so clients can
  work with the collection names directly. There is no need to work with collection ids
  on the client side anymore.
  This change will likely require adjustments to API calls issued by clients, and also
  requires a change in how clients handle the _id value of returned documents. Previously,
  the _id value of returned documents contained the collection id, a slash separator and
  the document number. Since 1.2, _id will contain the collection name, a slash separator
  and the document key. The same applies to the _from and _to attribute values of edges
  that are returned by ArangoDB.

  Also removed (now unnecessary) location header in responses of the collections REST API.
  The location header was previously returned because it was necessary for clients.
  When clients created a collection, they specified the collection name. The collection
  id was generated on the server, but the client needed to use the server-generated
  collection id for further API calls, e.g. when creating edges etc. Therefore, the
  full collection URL, also containing the collection id, was returned by the server in
  responses to the collection API, in the HTTP location header.
  Returning the location header has become unnecessary in ArangoDB 1.2 because users
  can access collections by name and do not need to care about collection ids.


v1.1.3 (2013-XX-XX)
-------------------

* fix case when an error message was looked up for an error code but no error
  message was found. In this case a NULL ptr was returned and not checked everywhere.
  The place this error popped up was when inserting into a non-unique hash index
  failed with a specific, invalid error code.

* fixed issue #381:  db._collection("_users").getIndexes();

* fixed issue #379: arango-password fatal issue javscript.startup-directory

* fixed issue #372: Command-Line Options for the Authentication and Authorization


v1.1.2 (2013-01-20)
-------------------

* upgraded to mruby 2013-01-20 583983385b81c21f82704b116eab52d606a609f4

* fixed issue #357: Some spelling and grammar errors

* fixed issue #355: fix quotes in pdf manual

* fixed issue #351: Strange arangosh error message for long running query

* fixed randomly hanging connections in arangosh on MacOS

* added "any" query method: this returns a random document from a collection. It
  is also available via REST HTTP at /_api/simple/any.

* added deployment tool

* added getPeerVertex

* small fix for logging of long messages: the last character of log messages longer
  than 256 bytes was not logged.

* fixed truncation of human-readable log messages for web interface: the trailing \0
  byte was not appended for messages longer than 256 bytes

* fixed issue #341: ArangoDB crashes when stressed with Batch jobs
  Contrary to the issue title, this did not have anything to do with batch jobs but
  with too high memory usage. The memory usage of ArangoDB is now reduced for cases
   when there are lots of small collections with few documents each

* started with issue #317: Feature Request (from Google Groups): DATE handling

* backported issue #300: Extend arangoImp to Allow importing resultset-like
  (list of documents) formatted files

* fixed issue #337: "WaitForSync" on new collection does not work on Win/X64

* fixed issue #336: Collections REST API docs

* fixed issue #335: mmap errors due to wrong memory address calculation

* fixed issue #332: arangoimp --use-ids parameter seems to have no impact

* added option '--server.disable-authentication' for arangosh as well. No more passwd
  prompts if not needed

* fixed issue #330: session logging for arangosh

* fixed issue #329: Allow passing script file(s) as parameters for arangosh to run

* fixed issue #328: 1.1 compile warnings

* fixed issue #327: Javascript parse errors in front end


v1.1.1 (2012-12-18)
-------------------

* fixed issue #339: DELETE /_api/cursor/cursor-identifier return incollect errorNum

  The fix for this has led to a signature change of the function actions.resultNotFound().
  The meaning of parameter #3 for This function has changed from the error message string
  to the error code. The error message string is now parameter #4.
  Any client code that uses this function in custom actions must be adjusted.

* fixed issue #321: Problem upgrading arangodb 1.0.4 to 1.1.0 with Homebrew (OSX 10.8.2)

* fixed issue #230: add navigation and search for online documentation

* fixed issue #315: Strange result in PATH

* fixed issue #323: Wrong function returned in error message of AQL CHAR_LENGTH()

* fixed some log errors on startup / shutdown due to pid file handling and changing
  of directories


v1.1.0 (2012-12-05)
-------------------

* WARNING:
  arangod now performs a database version check at startup. It will look for a file
  named "VERSION" in its database directory. If the file is not present, arangod will
  perform an automatic upgrade of the database directory. This should be the normal
  case when upgrading from ArangoDB 1.0 to ArangoDB 1.1.

  If the VERSION file is present but is from an older version of ArangoDB, arangod
  will refuse to start and ask the user to run a manual upgrade first. A manual upgrade
  can be performed by starting arangod with the option `--upgrade`.

  This upgrade procedure shall ensure that users have full control over when they
  perform any updates/upgrades of their data, and can plan backups accordingly. The
  procedure also guarantees that the server is not run without any required system
  collections or with in incompatible data state.

* added AQL function DOCUMENT() to retrieve a document by its _id value

* fixed issue #311: fixed segfault on unload

* fixed issue #309: renamed stub "import" button from web interface

* fixed issue #307: added WaitForSync column in collections list in in web interface

* fixed issue #306: naming in web interface

* fixed issue #304: do not clear AQL query text input when switching tabs in
  web interface

* fixed issue #303: added documentation about usage of var keyword in web interface

* fixed issue #301: PATCH does not work in web interface

# fixed issue #269: fix make distclean & clean

* fixed issue #296: system collections not usable from AQL

* fixed issue #295: deadlock on shutdown

* added collection type label to web interface

* fixed issue #290: the web interface now disallows creating non-edges in edge collections
  when creating collections via the web interface, the collection type must also be
  specified (default is document collection)

* fixed issue #289: tab-completion does not insert any spaces

* fixed issue #282: fix escaping in web interface

* made AQL function NOT_NULL take any number of arguments. Will now return its
  first argument that is not null, or null if all arguments are null. This is downwards
  compatible.

* changed misleading AQL function name NOT_LIST() to FIRST_LIST() and slightly changed
  the behavior. The function will now return its first argument that is a list, or null
  if none of the arguments are lists.
  This is mostly downwards-compatible. The only change to the previous implementation in
  1.1-beta will happen if two arguments were passed and the 1st and 2nd arguments were
  both no lists. In previous 1.1, the 2nd argument was returned as is, but now null
  will be returned.

* add AQL function FIRST_DOCUMENT(), with same behavior as FIRST_LIST(), but working
  with documents instead of lists.

* added UPGRADING help text

* fixed issue #284: fixed Javascript errors when adding edges/vertices without own
  attributes

* fixed issue #283: AQL LENGTH() now works on documents, too

* fixed issue #281: documentation for skip lists shows wrong example

* fixed AQL optimizer bug, related to OR-combined conditions that filtered on the
  same attribute but with different conditions

* fixed issue #277: allow usage of collection names when creating edges
  the fix of this issue also implies validation of collection names / ids passed to
  the REST edge create method. edges with invalid collection ids or names in the
  "from" or "to" values will be rejected and not saved


v1.1.beta2 (2012-11-13)
-----------------------

* fixed arangoirb compilation

* fixed doxygen


v1.1.beta1 (2012-10-24)
-----------------------

* fixed AQL optimizer bug

* WARNING:
  - the user has changed from "arango" to "arangodb", the start script has changed from
    "arangod" to "arangodb", the database directory has changed from "/var/arangodb" to
    "/var/lib/arangodb" to be compliant with various Linux policies

  - In 1.1, we have introduced types for collections: regular documents go into document
    collections, and edges go into edge collections. The prefixing (db.xxx vs. edges.xxx)
    works slightly different in 1.1: edges.xxx can still be used to access collections,
    however, it will not determine the type of existing collections anymore. To create an
    edge collection 1.1, you can use db._createEdgeCollection() or edges._create().
    And there's of course also db._createDocumentCollection().
    db._create() is also still there and will create a document collection by default,
    whereas edges._create() will create an edge collection.

  - the admin web interface that was previously available via the simple URL suffix /
    is now available via a dedicated URL suffix only: /_admin/html
    The reason for this is that routing and URLs are now subject to changes by the end user,
    and only URLs parts prefixed with underscores (e.g. /_admin or /_api) are reserved
    for ArangoDB's internal usage.

* the server now handles requests with invalid Content-Length header values as follows:
  - if Content-Length is negative, the server will respond instantly with HTTP 411
    (length required)

  - if Content-Length is positive but shorter than the supplied body, the server will
    respond with HTTP 400 (bad request)

  - if Content-Length is positive but longer than the supplied body, the server will
    wait for the client to send the missing bytes. The server allows 90 seconds for this
    and will close the connection if the client does not send the remaining data

  - if Content-Length is bigger than the maximum allowed size (512 MB), the server will
    fail with HTTP 413 (request entity too large).

  - if the length of the HTTP headers is greater than the maximum allowed size (1 MB),
    the server will fail with HTTP 431 (request header fields too large)

* issue #265: allow optional base64 encoding/decoding of action response data

* issue #252: create _modules collection using arango-upgrade (note: arango-upgrade was
  finally replaced by the `--upgrade` option for arangod)

* issue #251: allow passing arbitrary options to V8 engine using new command line option:
  --javascript.v8-options. Using this option, the Harmony features or other settings in
  v8 can be enabled if the end user requires them

* issue #248: allow AQL optimizer to pull out completely uncorrelated subqueries to the
  top level, resulting in less repeated evaluation of the subquery

* upgraded to Doxygen 1.8.0

* issue #247: added AQL function MERGE_RECURSIVE

* issue #246: added clear() function in arangosh

* issue #245: Documentation: Central place for naming rules/limits inside ArangoDB

* reduced size of hash index elements by 50 %, allowing more index elements to fit in
  memory

* issue #235: GUI Shell throws Error:ReferenceError: db is not defined

* issue #229: methods marked as "under construction"

* issue #228: remove unfinished APIs (/_admin/config/*)

* having the OpenSSL library installed is now a prerequisite to compiling ArangoDB
  Also removed the --enable-ssl configure option because ssl is always required.

* added AQL functions TO_LIST, NOT_LIST

* issue #224: add optional Content-Id for batch requests

* issue #221: more documentation on AQL explain functionality. Also added
  ArangoStatement.explain() client method

* added db._createStatement() method on server as well (was previously available
  on the client only)

* issue #219: continue in case of "document not found" error in PATHS() function

* issue #213: make waitForSync overridable on specific actions

* changed AQL optimizer to use indexes in more cases. Previously, indexes might
  not have been used when in a reference expression the inner collection was
  specified last. Example: FOR u1 IN users FOR u2 IN users FILTER u1._id == u2._id
  Previously, this only checked whether an index could be used for u2._id (not
  possible). It was not checked whether an index on u1._id could be used (possible).
  Now, for expressions that have references/attribute names on both sides of the
  above as above, indexes are checked for both sides.

* issue #204: extend the CSV import by TSV and by user configurable
  separator character(s)

* issue #180: added support for batch operations

* added startup option --server.backlog-size
  this allows setting the value of the backlog for the listen() system call.
  the default value is 10, the maximum value is platform-dependent

* introduced new configure option "--enable-maintainer-mode" for
  ArangoDB maintainers. this option replaces the previous compile switches
  --with-boost-test, --enable-bison, --enable-flex and --enable-errors-dependency
  the individual configure options have been removed. --enable-maintainer-mode
  turns them all on.

* removed potentially unused configure option --enable-memfail

* fixed issue #197: HTML web interface calls /_admin/user-manager/session

* fixed issue #195: VERSION file in database directory

* fixed issue #193: REST API HEAD request returns a message body on 404

* fixed issue #188: intermittent issues with 1.0.0
  (server-side cursors not cleaned up in all cases, pthreads deadlock issue)

* issue #189: key store should use ISO datetime format bug

* issue #187: run arango-upgrade on server start (note: arango-upgrade was finally
  replaced by the `--upgrade` option for arangod)n

* fixed issue #183: strange unittest error

* fixed issue #182: manual pages

* fixed issue #181: use getaddrinfo

* moved default database directory to "/var/lib/arangodb" in accordance with
  http://www.pathname.com/fhs/pub/fhs-2.3.html

* fixed issue #179: strange text in import manual

* fixed issue #178: test for aragoimp is missing

* fixed issue #177: a misleading error message was returned if unknown variables
  were used in certain positions in an AQL query.

* fixed issue #176: explain how to use AQL from the arangosh

* issue #175: re-added hidden (and deprecated) option --server.http-port. This
  option is only there to be downwards-compatible to Arango 1.0.

* fixed issue #174: missing Documentation for `within`

* fixed issue #170: add db.<coll_name>.all().toArray() to arangosh help screen

* fixed issue #169: missing argument in Simple Queries

* added program arango-upgrade. This program must be run after installing ArangoDB
  and after upgrading from a previous version of ArangoDB. The arango-upgrade script
  will ensure all system collections are created and present in the correct state.
  It will also perform any necessary data updates.
  Note: arango-upgrade was finally replaced by the `--upgrade` option for arangod.

* issue #153: edge collection should be a flag for a collection
  collections now have a type so that the distinction between document and edge
  collections can now be done at runtime using a collection's type value.
  A collection's type can be queried in Javascript using the <collection>.type() method.

  When new collections are created using db._create(), they will be document
  collections by default. When edge._create() is called, an edge collection will be created.
  To explicitly create a collection of a specific/different type, use the methods
  _createDocumentCollection() or _createEdgeCollection(), which are available for
  both the db and the edges object.
  The Javascript objects ArangoEdges and ArangoEdgesCollection have been removed
  completely.
  All internal and test code has been adjusted for this, and client code
  that uses edges.* should also still work because edges is still there and creates
  edge collections when _create() is called.

  INCOMPATIBLE CHANGE: Client code might still need to be changed in the following aspect:
  Previously, collections did not have a type so documents and edges could be inserted
  in the same collection. This is now disallowed. Edges can only be inserted into
  edge collections now. As there were no collection types in 1.0, ArangoDB will perform
  an automatic upgrade when migrating from 1.0 to 1.1.
  The automatic upgrade will check every collection and determine its type as follows:
  - if among the first 50 documents in the collection there are documents with
    attributes "_from" and "_to", the collection is typed as an edge collection
  - if among the first 50 documents in the collection there are no documents with
    attributes "_from" and "_to", the collection is made as a document collection

* issue #150: call V8 garbage collection on server periodically

* issue #110: added support for partial updates

  The REST API for documents now offers an HTTP PATCH method to partially update
  documents. Overwriting/replacing documents is still available via the HTTP PUT method
  as before. The Javascript API in the shell also offers a new update() method in extension to
  the previously existing replace() method.


v1.0.4 (2012-11-12)
-------------------

* issue #275: strange error message in arangosh 1.0.3 at startup


v1.0.3 (2012-11-08)
-------------------

* fixed AQL optimizer bug

* issue #273: fixed segfault in arangosh on HTTP 40x

* issue #265: allow optional base64 encoding/decoding of action response data

* issue #252: _modules collection not created automatically


v1.0.2 (2012-10-22)
-------------------

* repository CentOS-X.Y moved to CentOS-X, same for Debian

* bugfix for rollback from edges

* bugfix for hash indexes

* bugfix for StringBuffer::erase_front

* added autoload for modules

* added AQL function TO_LIST


v1.0.1 (2012-09-30)
-------------------

* draft for issue #165: front-end application howto

* updated mruby to cf8fdea4a6598aa470e698e8cbc9b9b492319d

* fix for issue #190: install doesn't create log directory

* fix for issue #194: potential race condition between creating and dropping collections

* fix for issue #193: REST API HEAD request returns a message body on 404

* fix for issue #188: intermittent issues with 1.0.0

* fix for issue #163: server cannot create collection because of abandoned files

* fix for issue #150: call V8 garbage collection on server periodically


v1.0.0 (2012-08-17)
-------------------

* fix for issue #157: check for readline and ncurses headers, not only libraries


v1.0.beta4 (2012-08-15)
-----------------------

* fix for issue #152: fix memleak for barriers


v1.0.beta3 (2012-08-10)
-----------------------

* fix for issue #151: Memleak, collection data not removed

* fix for issue #149: Inconsistent port for admin interface

* fix for issue #163: server cannot create collection because of abandoned files

* fix for issue #157: check for readline and ncurses headers, not only libraries

* fix for issue #108: db.<collection>.truncate() inefficient

* fix for issue #109: added startup note about cached collection names and how to
  refresh them

* fix for issue #156: fixed memleaks in /_api/import

* fix for issue #59: added tests for /_api/import

* modified return value for calls to /_api/import: now, the attribute "empty" is
  returned as well, stating the number of empty lines in the input. Also changed the
  return value of the error code attribute ("errorNum") from 1100 ("corrupted datafile")
  to 400 ("bad request") in case invalid/unexpected JSON data was sent to the server.
  This error code is more appropriate as no datafile is broken but just input data is
  incorrect.

* fix for issue #152: Memleak for barriers

* fix for issue #151: Memleak, collection data not removed

* value of --database.maximal-journal-size parameter is now validated on startup. If
  value is smaller than the minimum value (currently 1048576), an error is thrown and
  the server will not start. Before this change, the global value of maximal journal
  size was not validated at server start, but only on collection level

* increased sleep value in statistics creation loop from 10 to 500 microseconds. This
  reduces accuracy of statistics values somewhere after the decimal points but saves
  CPU time.

* avoid additional sync() calls when writing partial shape data (attribute name data)
  to disk. sync() will still be called when the shape marker (will be written after
  the attributes) is written to disk

* issue #147: added flag --database.force-sync-shapes to force synching of shape data
  to disk. The default value is true so it is the same behavior as in version 1.0.
  if set to false, shape data is synched to disk if waitForSync for the collection is
  set to true, otherwise, shape data is not synched.

* fix for issue #145: strange issue on Travis: added epsilon for numeric comparison in
  geo index

* fix for issue #136: adjusted message during indexing

* issue #131: added timeout for HTTP keep-alive connections. The default value is 300
  seconds. There is a startup parameter server.keep-alive-timeout to configure the value.
  Setting it to 0 will disable keep-alive entirely on the server.

* fix for issue #137: AQL optimizer should use indexes for ref accesses with
  2 named attributes


v1.0.beta2 (2012-08-03)
-----------------------

* fix for issue #134: improvements for centos RPM

* fixed problem with disable-admin-interface in config file


v1.0.beta1 (2012-07-29)
-----------------------

* fixed issue #118: We need a collection "debugger"

* fixed issue #126: Access-Shaper must be cached

* INCOMPATIBLE CHANGE: renamed parameters "connect-timeout" and "request-timeout"
  for arangosh and arangoimp to "--server.connect-timeout" and "--server.request-timeout"

* INCOMPATIBLE CHANGE: authorization is now required on the server side
  Clients sending requests without HTTP authorization will be rejected with HTTP 401
  To allow backwards compatibility, the server can be started with the option
  "--server.disable-authentication"

* added options "--server.username" and "--server.password" for arangosh and arangoimp
  These parameters must be used to specify the user and password to be used when
  connecting to the server. If no password is given on the command line, arangosh/
  arangoimp will interactively prompt for a password.
  If no user name is specified on the command line, the default user "root" will be
  used.

* added startup option "--server.ssl-cipher-list" to determine which ciphers to
  use in SSL context. also added SSL_OP_CIPHER_SERVER_PREFERENCE to SSL default
  options so ciphers are tried in server and not in client order

* changed default SSL protocol to TLSv1 instead of SSLv2

* changed log-level of SSL-related messages

* added SSL connections if server is compiled with OpenSSL support. Use --help-ssl

* INCOMPATIBLE CHANGE: removed startup option "--server.admin-port".
  The new endpoints feature (see --server.endpoint) allows opening multiple endpoints
  anyway, and the distinction between admin and "other" endpoints can be emulated
  later using privileges.

* INCOMPATIBLE CHANGE: removed startup options "--port", "--server.port", and
  "--server.http-port" for arangod.
  These options have been replaced by the new "--server.endpoint" parameter

* INCOMPATIBLE CHANGE: removed startup option "--server" for arangosh and arangoimp.
  These options have been replaced by the new "--server.endpoint" parameter

* Added "--server.endpoint" option to arangod, arangosh, and arangoimp.
  For arangod, this option allows specifying the bind endpoints for the server
  The server can be bound to one or multiple endpoints at once. For arangosh
  and arangoimp, the option specifies the server endpoint to connect to.
  The following endpoint syntax is currently supported:
  - tcp://host:port or http@tcp://host:port (HTTP over IPv4)
  - tcp://[host]:port or http@tcp://[host]:port (HTTP over IPv6)
  - ssl://host:port or http@tcp://host:port (HTTP over SSL-encrypted IPv4)
  - ssl://[host]:port or http@tcp://[host]:port (HTTP over SSL-encrypted IPv6)
  - unix:///path/to/socket or http@unix:///path/to/socket (HTTP over UNIX socket)

  If no port is specified, the default port of 8529 will be used.

* INCOMPATIBLE CHANGE: removed startup options "--server.require-keep-alive" and
  "--server.secure-require-keep-alive".
  The server will now behave as follows which should be more conforming to the
  HTTP standard:
  * if a client sends a "Connection: close" header, the server will close the
    connection
  * if a client sends a "Connection: keep-alive" header, the server will not
    close the connection
  * if a client does not send any "Connection" header, the server will assume
    "keep-alive" if the request was an HTTP/1.1 request, and "close" if the
    request was an HTTP/1.0 request

* (minimal) internal optimizations for HTTP request parsing and response header
  handling

* fixed Unicode unescaping bugs for \f and surrogate pairs in BasicsC/strings.c

* changed implementation of TRI_BlockCrc32 algorithm to use 8 bytes at a time

* fixed issue #122: arangod doesn't start if <log.file> cannot be created

* fixed issue #121: wrong collection size reported

* fixed issue #98: Unable to change journalSize

* fixed issue #88: fds not closed

* fixed escaping of document data in HTML admin front end

* added HTTP basic authentication, this is always turned on

* added server startup option --server.disable-admin-interface to turn off the
  HTML admin interface

* honor server startup option --database.maximal-journal-size when creating new
  collections without specific journalsize setting. Previously, these
  collections were always created with journal file sizes of 32 MB and the
  --database.maximal-journal-size setting was ignored

* added server startup option --database.wait-for-sync to control the default
  behavior

* renamed "--unit-tests" to "--javascript.unit-tests"


v1.0.alpha3 (2012-06-30)
------------------------

* fixed issue #116: createCollection=create option doesn't work

* fixed issue #115: Compilation issue under OSX 10.7 Lion & 10.8 Mountain Lion
  (homebrew)

* fixed issue #114: image not found

* fixed issue #111: crash during "make unittests"

* fixed issue #104: client.js -> ARANGO_QUIET is not defined


v1.0.alpha2 (2012-06-24)
------------------------

* fixed issue #112: do not accept document with duplicate attribute names

* fixed issue #103: Should we cleanup the directory structure

* fixed issue #100: "count" attribute exists in cursor response with "count:
  false"

* fixed issue #84 explain command

* added new MRuby version (2012-06-02)

* added --log.filter

* cleanup of command line options:
** --startup.directory => --javascript.startup-directory
** --quite => --quiet
** --gc.interval => --javascript.gc-interval
** --startup.modules-path => --javascript.modules-path
** --action.system-directory => --javascript.action-directory
** --javascript.action-threads => removed (is now the same pool as --server.threads)

* various bug-fixes

* support for import

* added option SKIP_RANGES=1 for make unittests

* fixed several range-related assertion failures in the AQL query optimizer

* fixed AQL query optimizations for some edge cases (e.g. nested subqueries with
  invalid constant filter expressions)


v1.0.alpha1 (2012-05-28)
------------------------

Alpha Release of ArangoDB 1.0