diff options
Diffstat (limited to 'sql/transaction.cc')
| -rw-r--r-- | sql/transaction.cc | 36 |
1 files changed, 9 insertions, 27 deletions
diff --git a/sql/transaction.cc b/sql/transaction.cc index 543e0b7ad38..d9d0d402ec7 100644 --- a/sql/transaction.cc +++ b/sql/transaction.cc @@ -1,4 +1,5 @@ /* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved. + Copyright (c) 2009, 2021, MariaDB Corporation. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -696,32 +697,6 @@ bool trans_rollback_to_savepoint(THD *thd, LEX_STRING name) if (WSREP_ON) wsrep_register_hton(thd, thd->in_multi_stmt_transaction_mode()); - /** - Checking whether it is safe to release metadata locks acquired after - savepoint, if rollback to savepoint is successful. - - Whether it is safe to release MDL after rollback to savepoint depends - on storage engines participating in transaction: - - - InnoDB doesn't release any row-locks on rollback to savepoint so it - is probably a bad idea to release MDL as well. - - Binary log implementation in some cases (e.g when non-transactional - tables involved) may choose not to remove events added after savepoint - from transactional cache, but instead will write them to binary - log accompanied with ROLLBACK TO SAVEPOINT statement. Since the real - write happens at the end of transaction releasing MDL on tables - mentioned in these events (i.e. acquired after savepoint and before - rollback ot it) can break replication, as concurrent DROP TABLES - statements will be able to drop these tables before events will get - into binary log, - - For backward-compatibility reasons we always release MDL if binary - logging is off. - */ - bool mdl_can_safely_rollback_to_savepoint= - (!(mysql_bin_log.is_open() && thd->variables.sql_log_bin) || - ha_rollback_to_savepoint_can_release_mdl(thd)); - if (ha_rollback_to_savepoint(thd, sv)) res= TRUE; else if (((thd->variables.option_bits & OPTION_KEEP_LOG) || @@ -733,7 +708,14 @@ bool trans_rollback_to_savepoint(THD *thd, LEX_STRING name) thd->transaction.savepoints= sv; - if (!res && mdl_can_safely_rollback_to_savepoint) + if (res) + /* An error occurred during rollback; we cannot release any MDL */; + else if (thd->variables.sql_log_bin && mysql_bin_log.is_open()) + /* In some cases (such as with non-transactional tables) we may + choose to preserve events that were added after the SAVEPOINT, + delimiting them by SAVEPOINT and ROLLBACK TO SAVEPOINT statements. + Prematurely releasing MDL on such objects would break replication. */; + else if (ha_rollback_to_savepoint_can_release_mdl(thd)) thd->mdl_context.rollback_to_savepoint(sv->mdl_savepoint); DBUG_RETURN(MY_TEST(res)); |