MDEV-12914: Engine for temporary tables which are implicitly created as RocksDB is substituted silently

- There should be no substitution if engine exists, only when doesn't
exist
- Handling of an error when sys_var `default_tmp_storage_engine` is
assigned to unsupported engine.
- rocksdb doesn't support embedded server ebfc4e6ad0 so is excluded

Closes PR #774
Reviewed by: serg@mariadb.com
             vicentiu@mariadb.org

mysql-test/main/partition_error.result

@@ -754,7 +754,7 @@ ERROR HY000: Field 'c' is of a not allowed type for this type of partitioning
 #
 CREATE TABLE t1 (a INT) PARTITION BY HASH(a);
 CREATE TEMPORARY TABLE tmp_t1 LIKE t1;
-ERROR HY000: Partitioned tables do not support CREATE TEMPORARY TABLE
+ERROR HY000: Table storage engine 'partition' does not support the create option 'TEMPORARY'
 DROP TABLE t1;
 #
 # Bug#42954: SQL MODE 'NO_DIR_IN_CREATE' does not work with

mysql-test/main/partition_error.test

@@ -788,7 +788,7 @@ PARTITION BY HASH (c) PARTITIONS 4;
 --echo # with temporary table and partitions
 --echo #
 CREATE TABLE t1 (a INT) PARTITION BY HASH(a);
---error ER_FEATURE_NOT_SUPPORTED_WITH_PARTITIONING
+--error ER_ILLEGAL_HA_CREATE_OPTION
 CREATE TEMPORARY TABLE tmp_t1 LIKE t1;
 DROP TABLE t1;
 --echo #

mysql-test/suite/sys_vars/r/default_tmp_storage_engine_rocksdb.result

@@ -0,0 +1,51 @@
+#
+# MDEV-12914: Engine for temporary tables which are implicitly
+#             created as RocksDB is substitued siliently with MyIsam
+SET default_tmp_storage_engine = engine_doesnt_exist;
+ERROR 42000: Unknown storage engine 'engine_doesnt_exist'
+SET default_tmp_storage_engine = rocksdb;
+ERROR HY000: Table storage engine 'ROCKSDB' does not support the create option 'TEMPORARY'
+SET default_tmp_storage_engine = CONCAT('rocks','db');
+ERROR HY000: Table storage engine 'ROCKSDB' does not support the create option 'TEMPORARY'
+CREATE TABLE t1 (i int) ENGINE = RocksDB;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `i` int(11) DEFAULT NULL
+) ENGINE=ROCKSDB DEFAULT CHARSET=latin1
+CREATE TEMPORARY TABLE t2 LIKE t1;
+ERROR HY000: Table storage engine 'ROCKSDB' does not support the create option 'TEMPORARY'
+DROP TABLE t1;
+SET default_storage_engine = DEFAULT;
+SET default_tmp_storage_engine = DEFAULT;
+CREATE TABLE t1 (t int);
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `t` int(11) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+CREATE TEMPORARY TABLE t2 LIKE t1;
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TEMPORARY TABLE `t2` (
+  `t` int(11) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1, t2;
+SET default_storage_engine = rocksdb;
+SET default_tmp_storage_engine = default;
+CREATE TABLE t1 (t int);
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `t` int(11) DEFAULT NULL
+) ENGINE=ROCKSDB DEFAULT CHARSET=latin1
+CREATE TEMPORARY TABLE t2 LIKE t1;
+ERROR HY000: Table storage engine 'ROCKSDB' does not support the create option 'TEMPORARY'
+CREATE TEMPORARY TABLE t2 (t int);
+ERROR HY000: Table storage engine 'ROCKSDB' does not support the create option 'TEMPORARY'
+SET default_tmp_storage_engine = aria;
+CREATE TEMPORARY TABLE t2 (t int);
+DROP TABLE t2;
+CREATE TEMPORARY TABLE t2 LIKE t1;
+ERROR HY000: Table storage engine 'ROCKSDB' does not support the create option 'TEMPORARY'
+DROP TABLE t1;

mysql-test/suite/sys_vars/t/default_tmp_storage_engine_rocksdb.test

@@ -0,0 +1,52 @@
+--echo #
+--echo # MDEV-12914: Engine for temporary tables which are implicitly
+--echo #             created as RocksDB is substitued siliently with MyIsam
+
+--source include/have_rocksdb.inc
+--source include/not_embedded.inc
+--error ER_UNKNOWN_STORAGE_ENGINE
+SET default_tmp_storage_engine = engine_doesnt_exist;
+--error ER_ILLEGAL_HA_CREATE_OPTION
+SET default_tmp_storage_engine = rocksdb;
+--error ER_ILLEGAL_HA_CREATE_OPTION
+SET default_tmp_storage_engine = CONCAT('rocks','db');
+
+CREATE TABLE t1 (i int) ENGINE = RocksDB;
+SHOW CREATE TABLE t1;
+
+--error ER_ILLEGAL_HA_CREATE_OPTION
+CREATE TEMPORARY TABLE t2 LIKE t1;
+
+DROP TABLE t1;
+
+SET default_storage_engine = DEFAULT;
+SET default_tmp_storage_engine = DEFAULT;
+
+CREATE TABLE t1 (t int);
+SHOW CREATE TABLE t1;
+CREATE TEMPORARY TABLE t2 LIKE t1;
+SHOW CREATE TABLE t2;
+
+DROP TABLE t1, t2;
+
+SET default_storage_engine = rocksdb;
+# setting default or null for tmp SE should use default SE
+SET default_tmp_storage_engine = default;
+
+CREATE TABLE t1 (t int);
+SHOW CREATE TABLE t1;
+
+--error ER_ILLEGAL_HA_CREATE_OPTION
+CREATE TEMPORARY TABLE t2 LIKE t1;
+
+--error ER_ILLEGAL_HA_CREATE_OPTION
+CREATE TEMPORARY TABLE t2 (t int);
+
+SET default_tmp_storage_engine = aria;
+CREATE TEMPORARY TABLE t2 (t int);
+DROP TABLE t2;
+
+--error ER_ILLEGAL_HA_CREATE_OPTION
+CREATE TEMPORARY TABLE t2 LIKE t1;
+
+DROP TABLE t1;

mysql-test/suite/sysschema/r/pr_diagnostics.result

@@ -6,8 +6,6 @@ SET @sys.debug                        = 'OFF',
 @sys.diagnostics.allow_i_s_tables = 'OFF',
 @sys.diagnostics.include_raw      = 'OFF';
 CALL sys.diagnostics(0, 0, 'full');
-summary
-Disabled 1 thread
 ERROR 45000: in_max_runtime must be greater than 0
 CALL sys.diagnostics(2, 0, 'full');
 ERROR 45000: in_interval must be greater than 0

mysql-test/suite/sysschema/t/pr_diagnostics.test

@@ -19,6 +19,7 @@ SET @sys.debug                        = 'ON',
     @sys.diagnostics.allow_i_s_tables = 'ON',
     @sys.diagnostics.include_raw      = 'ON';
 
+--error ER_ILLEGAL_HA_CREATE_OPTION
 CALL sys.diagnostics(4, 2, 'full');
 
 SET @sys.debug                        = 'OFF',

sql/sql_table.cc

@@ -11470,16 +11470,11 @@ bool check_engine(THD *thd, const char *db_name,
   if (create_info->tmp_table() &&
       ha_check_storage_engine_flag(*new_engine, HTON_TEMPORARY_NOT_SUPPORTED))
   {
-    if (create_info->used_fields & HA_CREATE_USED_ENGINE)
+    my_error(ER_ILLEGAL_HA_CREATE_OPTION, MYF(0),
-    {
+             hton_name(*new_engine)->str, "TEMPORARY");
-      my_error(ER_ILLEGAL_HA_CREATE_OPTION, MYF(0),
+    *new_engine= 0;
-               hton_name(*new_engine)->str, "TEMPORARY");
+    DBUG_RETURN(true);
-      *new_engine= 0;
-      DBUG_RETURN(true);
-    }
-    *new_engine= myisam_hton;
   }
-
   lex_string_set(&create_info->new_storage_engine_name,
                  ha_resolve_storage_engine_name(*new_engine));
   DBUG_RETURN(false);

sql/sys_vars.cc

@@ -741,6 +741,29 @@ static Sys_var_charptr_fscs Sys_character_sets_dir(
        READ_ONLY GLOBAL_VAR(charsets_dir), CMD_LINE(REQUIRED_ARG),
        DEFAULT(0));
 
+static bool check_engine_supports_temporary(sys_var *self, THD *thd, set_var *var)
+{
+  String str, *res;
+  LEX_CSTRING name;
+  if (!var->value || var->value->is_null())
+    return false;
+  res= var->value->val_str(&str);
+  res->get_value(&name);
+  plugin_ref plugin= ha_resolve_by_name(thd, &name, true);
+  DBUG_ASSERT(plugin);
+  handlerton *hton= plugin_hton(plugin);
+  DBUG_ASSERT(hton);
+  if (ha_check_storage_engine_flag(hton, HTON_TEMPORARY_NOT_SUPPORTED))
+  {
+    my_error(ER_ILLEGAL_HA_CREATE_OPTION, MYF(0), hton_name(hton)->str,
+             "TEMPORARY");
+    plugin_unlock(thd, plugin);
+    return true;
+  }
+  plugin_unlock(thd, plugin);
+  return false;
+}
+
 static bool check_not_null(sys_var *self, THD *thd, set_var *var)
 {
   return var->value && var->value->is_null();
@@ -4239,7 +4262,8 @@ static Sys_var_plugin Sys_storage_engine(
 static Sys_var_plugin Sys_default_tmp_storage_engine(
        "default_tmp_storage_engine", "The default storage engine for user-created temporary tables",
        SESSION_VAR(tmp_table_plugin), NO_CMD_LINE,
-       MYSQL_STORAGE_ENGINE_PLUGIN, DEFAULT(&default_tmp_storage_engine));
+       MYSQL_STORAGE_ENGINE_PLUGIN, DEFAULT(&default_tmp_storage_engine),
+       NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(check_engine_supports_temporary));
 
 static Sys_var_plugin Sys_enforce_storage_engine(
        "enforce_storage_engine", "Force the use of a storage engine for new tables",