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.

Author: bsrikanth-mariadb

mysql-test/main/opt_context_store_ddls.result

@@ -542,4 +542,39 @@ 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;
+
+
+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()->discover_table)
+    {
       continue;
+    }
 
     /*
       A query can use the same table multiple times. Do not dump the
@@ -809,8 +813,11 @@ 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 (tbl->is_view())
+    /* If this is a VIEW or a SEQUENCE table as
+      CREATE SEQUENCE s1;
+      explain SELECT * FROM s1;
+    we've stored its DDL and we're done. */
+    if (tbl->is_view() || (tbl->table && tbl->table->s->sequence))
       continue;
 
     /* No, it's a base table */