Hi, Michael! On Apr 13, Michael Widenius wrote:

revision-id: bc5c062b1d1 (mariadb-10.5.2-124-gbc5c062b1d1) parent(s): fb29c886701 author: Michael Widenius <monty@mariadb.com> committer: Michael Widenius <monty@mariadb.com> timestamp: 2020-04-09 01:37:02 +0300 message:

Don't try to open temporary tables if there are no temporary tables

Why?

diff --git a/sql/sql_base.cc b/sql/sql_base.cc index 4d7a7606136..be19a2e1d82 100644 --- a/sql/sql_base.cc +++ b/sql/sql_base.cc @@ -3704,9 +3704,9 @@ open_and_process_table(THD *thd, TABLE_LIST *tables, uint *counter, uint flags, The problem is that since those attributes are not set in merge children, another round of PREPARE will not help. */ - error= thd->open_temporary_table(tables); - - if (!error && !tables->table) + if (!thd->has_temporary_tables() || + (!(error= thd->open_temporary_table(tables)) && + !tables->table))

please don't write conditions like that. keep it as before, two statements: if (thd->has_temporary_tables()) error= thd->open_temporary_table(tables); if (!error && !tables->table)

error= open_table(thd, tables, ot_ctx);

thd->pop_internal_handler(); @@ -3723,9 +3723,9 @@ open_and_process_table(THD *thd, TABLE_LIST *tables, uint *counter, uint flags, Repair_mrg_table_error_handler repair_mrg_table_handler; thd->push_internal_handler(&repair_mrg_table_handler);

- error= thd->open_temporary_table(tables); - - if (!error && !tables->table) + if (!thd->has_temporary_tables() || + (!(error= thd->open_temporary_table(tables)) && + !tables->table)) error= open_table(thd, tables, ot_ctx);

thd->pop_internal_handler(); @@ -3740,7 +3740,8 @@ open_and_process_table(THD *thd, TABLE_LIST *tables, uint *counter, uint flags, still might need to look for a temporary table if this table list element corresponds to underlying table of a merge table. */ - error= thd->open_temporary_table(tables); + if (thd->has_temporary_tables()) + error= thd->open_temporary_table(tables); }

if (!error && !tables->table) diff --git a/sql/temporary_tables.cc b/sql/temporary_tables.cc index 407072a7b49..553460729a1 100644 --- a/sql/temporary_tables.cc +++ b/sql/temporary_tables.cc @@ -338,9 +338,9 @@ bool THD::open_temporary_table(TABLE_LIST *tl) have invalid db or table name. Instead THD::open_tables() should be used. */ - DBUG_ASSERT(!tl->derived && !tl->schema_table); + DBUG_ASSERT(!tl->derived && !tl->schema_table && has_temporary_tables());

please, never do asserts with &&-ed conditions, this should be DBUG_ASSERT(!tl->derived); DBUG_ASSERT(!tl->schema_table); DBUG_ASSERT(has_temporary_tables());

- if (tl->open_type == OT_BASE_ONLY || !has_temporary_tables()) + if (tl->open_type == OT_BASE_ONLY) { DBUG_PRINT("info", ("skip_temporary is set or no temporary tables")); DBUG_RETURN(false);

Regards, Sergei VP of MariaDB Server Engineering and security@mariadb.org