MDEV-40388: sequence.simple fails on replay

When recording is enabled for the query such as,
explain select * from seq_1_to_10;
it recorded the table context having a DDL definition as: -

CREATE TABLE `seq_1_to_10` (
    ->   `seq` bigint(20) unsigned NOT NULL,
    ->   PRIMARY KEY (`seq`)
    -> ) ENGINE=SEQUENCE DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci;

Now, when that context is replayed, the DDL statement is executed.
But, we cannot create such a table, and instead it errors out saying
ERROR 1050 (42S01): Table 'seq_1_to_10' already exists.

Solution is to not record a DDL statement or any stats for sequence
tables such as seq_1_to_10.

Also, there is a different way to use sequences as: -
  Create sequence s1;
  Explain select * from s1;

Here, we should be recording the DDL statement, but no need to store the
stats for it. However, we didn't record the DDL statement earlier.
Moreover, sequence's next value should be the same in the replay environment.

Solution here is to record the DDL for such a sequence, and
set its start value as the recorded environment's previous value.

Author: bsrikanth-mariadb

mysql-test/main/opt_context_replay_basic.result

@@ -549,4 +549,28 @@ select context like '%bar%' from information_schema.optimizer_context;
 context like '%bar%'
 1
 drop table t1;
+#
+# MDEV-40388: sequence.simple fails on replay
+#
+set optimizer_record_context=0;
+create sequence s1;
+select setval(s1, 10);
+setval(s1, 10)
+10
+set optimizer_record_context=1;
+select nextval(s1) as nv;
+nv
+11
+select context into dumpfile "../../tmp/dump1.sql"
+from information_schema.optimizer_context;
+set optimizer_record_context=0;
+drop table s1;
+set optimizer_replay_context='opt_context';
+# Get the last recorded value from the sequence; must have same output as above
+select lastval(s1) as nv;
+nv
+11
+set optimizer_replay_context='';
+drop table s1;
+# End of 13.1 tests
 drop database db1;

mysql-test/main/opt_context_replay_basic.test

@@ -1,6 +1,6 @@
 --source include/not_embedded.inc
 --source include/have_sequence.inc
---source include/no_view_protocol.inc
+--source include/no_protocol.inc
 --echo #enable optimizer_record_context
 set optimizer_trace=0;
 set optimizer_record_context=ON;
@@ -351,4 +351,31 @@ explain select * from t1 where a >'foo' or a < 'bar';
 select context like '%bar%' from information_schema.optimizer_context;
 
 drop table t1;
+
+--echo #
+--echo # MDEV-40388: sequence.simple fails on replay
+--echo #
+set optimizer_record_context=0;
+create sequence s1;
+select setval(s1, 10);
+set optimizer_record_context=1;
+select nextval(s1) as nv;
+select context into dumpfile "../../tmp/dump1.sql"
+from information_schema.optimizer_context;
+set optimizer_record_context=0;
+drop table s1;
+--disable_query_log
+--disable_result_log
+--source "$MYSQLTEST_VARDIR/tmp/dump1.sql"
+--enable_query_log
+--enable_result_log
+set optimizer_replay_context='opt_context';
+--echo # Get the last recorded value from the sequence; must have same output as above
+select lastval(s1) as nv;
+
+set optimizer_replay_context='';
+--remove_file "$MYSQLTEST_VARDIR/tmp/dump1.sql"
+drop table s1;
+--echo # End of 13.1 tests
+
 drop database db1;

mysql-test/main/opt_context_store_ddls.result

@@ -542,4 +542,41 @@ CREATE TABLE `t1` (
 
 
 drop table t1, t2;
+#
+# MDEV-40388: sequence.simple fails on replay
+#
+create sequence s1;
+# context result should have the ddl
+explain select * from s1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	s1	system	NULL	NULL	NULL	NULL	1	
+# == Optimizer Context Tables
+name
+# === Optimizer Context DDLs
+@ddls
+CREATE TABLE `s1` (
+  `next_not_cached_value` bigint(21) NOT NULL,
+  `minimum_value` bigint(21) NOT NULL,
+  `maximum_value` bigint(21) NOT NULL,
+  `start_value` bigint(21) NOT NULL COMMENT 'start value when sequences is created or value if RESTART is used',
+  `increment` bigint(21) NOT NULL COMMENT 'increment value',
+  `cache_size` bigint(21) unsigned NOT NULL,
+  `cycle_option` tinyint(1) unsigned NOT NULL COMMENT '0 if no cycles are allowed, 1 if the sequence should begin a new cycle when maximum_value is passed',
+  `cycle_count` bigint(21) NOT NULL COMMENT 'How many cycles have been done'
+) ENGINE=MyISAM SEQUENCE=1;
+
+SELECT SETVAL(db1.s1, 1);
+
+
+drop table s1;
+# no ddl should be captured here
+explain select * from seq_1_to_10;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	seq_1_to_10	index	NULL	PRIMARY	8	NULL	10	Using index
+# == Optimizer Context Tables
+name
+# === Optimizer Context DDLs
+@ddls
+
+# End of 13.1 tests
 drop database db1;

mysql-test/main/opt_context_store_ddls.test

@@ -312,4 +312,19 @@ delete t1.*, t2.* from t1, t2 where t1.id1 = t2.id2;
 
 drop table t1, t2;
 
+--echo #
+--echo # MDEV-40388: sequence.simple fails on replay
+--echo #
+create sequence s1;
+--echo # context result should have the ddl
+explain select * from s1;
+--source include/opt_context_list_tables_ddls.inc
+drop table s1;
+
+--echo # no ddl should be captured here
+explain select * from seq_1_to_10;
+--source include/opt_context_list_tables_ddls.inc
+
+--echo # End of 13.1 tests
+
 drop database db1;

mysql-test/main/opt_context_store_stats.result

@@ -591,3 +591,19 @@ table_name	file_stat_records	index_name	rec_per_key
 index_name	ranges	num_rows	max_index_blocks	max_row_blocks
 # == End of optimizer context
 drop table s1;
+#
+# MDEV-40388: sequence.simple fails on replay
+# Table context should *not* be recorded for seq
+#
+set optimizer_record_context=ON;
+explain select * from seq_1_to_10;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	seq_1_to_10	index	NULL	PRIMARY	8	NULL	10	Using index
+# == Optimizer Context
+# === Tables
+# Tables in the context
+table_name	file_stat_records	index_name	rec_per_key
+# === Range accesses
+index_name	ranges	num_rows	max_index_blocks	max_row_blocks
+# == End of optimizer context
+# End of 13.1 tests

mysql-test/main/opt_context_store_stats.test

@@ -432,3 +432,14 @@ EXPLAIN select * from s1;
 
 --source include/opt_context_list_tables_and_ranges.inc
 drop table s1;
+
+--echo #
+--echo # MDEV-40388: sequence.simple fails on replay
+--echo # Table context should *not* be recorded for seq
+--echo #
+set optimizer_record_context=ON;
+explain select * from seq_1_to_10;
+
+--source include/opt_context_list_tables_and_ranges.inc
+
+--echo # End of 13.1 tests

sql/opt_context_store_replay.cc

@@ -756,10 +756,14 @@ bool Optimizer_context_recorder::dump_sql_script(THD* thd, String &sql_script)
     append_table_or_view_name(tbl, &full_tbl_name);
 
     /*
-      Sequence table doesn't need CREATE TABLE or contain any stats
+      Sequence table such as seq_1_to_10 is a virtual table and so
+      doesn't need CREATE TABLE STATEMENT, and stats.
     */
-    if (tbl->table && tbl->table->s && tbl->table->s->sequence)
+    if (!tbl->is_view() && tbl->table && tbl->table->s->db_type() &&
+        tbl->table->s->db_type()->discover_table)
+    {
       continue;
+    }
 
     /*
       A query can use the same table multiple times. Do not dump the
@@ -809,10 +813,50 @@ bool Optimizer_context_recorder::dump_sql_script(THD* thd, String &sql_script)
     qry_ctx_script.append(ddl);
     qry_ctx_script.append(STRING_WITH_LEN(";\n\n"));
 
-    /* If this is a VIEW, we've stored its DDL and we're done. */
+    /* If this is a VIEW we've stored its DDL and we're done. */
     if (tbl->is_view())
       continue;
 
+    /*
+      if this is a SEQUENCE table defined as
+        CREATE SEQUENCE s1;
+      then, record the current value of s1 as well.
+      DDL for it has already been recorded.
+      No need to record stats.
+    */
+    if (tbl->table && tbl->table->s->sequence)
+    {
+      const char *key;
+      uint length= get_table_def_key(tbl, &key); // table def key = hash key
+      SEQUENCE_LAST_VALUE *entry= (SEQUENCE_LAST_VALUE *) my_hash_search(
+          &thd->sequences, (uchar *) key, length);
+      SEQUENCE *seq= tbl->table->s->sequence;
+      longlong value;
+      if (entry && !entry->check_version(tbl->table))
+      {
+        /*
+          Set the sequence so that the next NEXTVAL returns the value that
+          was last handed out (entry->value): SETVAL(x) makes the next
+          NEXTVAL return x + increment, so use entry->value - increment.
+          Keep the argument within the sequence bounds - for an ascending
+          sequence it may fall below min_value, for a descending one it may
+          rise above max_value, and SETVAL rejects out-of-range values.
+        */
+        longlong candidate= entry->value - seq->increment;
+        value= seq->increment > 0 ? MY_MAX(candidate, seq->min_value)
+                                  : MY_MIN(candidate, seq->max_value);
+      }
+      else
+        value= seq->reserved_until;
+      qry_ctx_script.append(STRING_WITH_LEN("SELECT SETVAL("));
+      qry_ctx_script.append(full_tbl_name);
+      qry_ctx_script.append(STRING_WITH_LEN(", "));
+      qry_ctx_script.append_longlong(value);
+      qry_ctx_script.append(STRING_WITH_LEN(");\n\n"));
+
+      continue;
+    }
+
     /* No, it's a base table */
     Json_writer_object ctx_wrapper(&ctx_writer);