Hi!

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"Sergey" == Sergey Vojtovich <svoj@mariadb.org> writes:

Sergey> revision-id: 3a8f101a173b987b314ba5fcc5c74d80ab56802b (mariadb-10.2.2-160-g3a8f101) Sergey> parent(s): c846ebe9df9adc90a5c25be0dce816c5d4302794 Sergey> committer: Sergey Vojtovich Sergey> timestamp: 2017-02-07 13:27:42 +0400 Sergey> message: Sergey> MDEV-11379 - AliSQL: [Feature] Issue#8: SELECT FOR UPDATE WAIT Sergey> Extended syntax so that it is now possible to set lock_wait_timeout for the Sergey> following statements: Sergey> SELECT ... FOR UPDATE [WAIT n|NOWAIT] Sergey> SELECT ... LOCK IN SHARED MODE [WAIT n|NOWAIT] Sergey> LOCK TABLE ... [WAIT n|NOWAIT] Sergey> This is amended AliSQL patch. We prefer Oracle syntax for [WAIT n|NOWAIT] Sergey> instead of original [WAIT [n]|NO_WAIT]. Agree it's better to use a syntax that someone else is using. Sergey> diff --git a/include/mysql/plugin.h b/include/mysql/plugin.h Sergey> index b3c71c65..b0a5849 100644 Sergey> --- a/include/mysql/plugin.h Sergey> +++ b/include/mysql/plugin.h Sergey> @@ -633,6 +633,7 @@ void thd_storage_lock_wait(MYSQL_THD thd, long long value); Sergey> int thd_tx_isolation(const MYSQL_THD thd); Sergey> int thd_tx_is_read_only(const MYSQL_THD thd); Sergey> int thd_rpl_is_parallel(const MYSQL_THD thd); Sergey> +unsigned long thd_lex_lock_wait_timeout(const MYSQL_THD thd); Sergey> /** Sergey> Create a temporary file. <cut> Sergey> +++ b/sql/sql_base.cc Sergey> @@ -2723,13 +2723,18 @@ Open_table_context::Open_table_context(THD *thd, uint flags) Sergey> :m_thd(thd), Sergey> m_failed_table(NULL), Sergey> m_start_of_statement_svp(thd->mdl_context.mdl_savepoint()), Sergey> - m_timeout(flags & MYSQL_LOCK_IGNORE_TIMEOUT ? Sergey> - LONG_TIMEOUT : thd->variables.lock_wait_timeout), Sergey> m_flags(flags), Sergey> m_action(OT_NO_ACTION), Sergey> m_has_locks(thd->mdl_context.has_locks()), Sergey> m_has_protection_against_grl(FALSE) Sergey> -{} Sergey> +{ Sergey> + if (flags & MYSQL_LOCK_IGNORE_TIMEOUT) Sergey> + m_timeout= LONG_TIMEOUT; Sergey> + else if (thd->lex->lock_wait_timeout == ULONG_MAX) Sergey> + m_timeout= thd->variables.lock_wait_timeout; Sergey> + else Sergey> + m_timeout= thd->lex->lock_wait_timeout; Sergey> +} Instead of adding thd->lex->lock_wait_timeout I suggest that we instead use the existing facititliy of SET STATEMENT innodb_lock_wait_timeout=xxx SELECT This has the following benefits: - We only need one innodb timeout variable, not two - Probably simpler code. Very few changes needed in InnoDB - One will get exactly same behaviour independent of the syntax that is used This would change the task to be implemented the following wat: - If WAIT|NOWAIT is used, change in sql_yacc.yy to use the SET STATEMENT facility to set innodb_lock_wait_timeout and lock_wait_timeout - Add support for nowait (timeout == 0 would mean nowait) I agree that having the new syntax is good as it's used by other databases and simpler than having to set two variables. Regards, Monty