Yup, innodb_locks_unsafe_for_binlog=1 fixes the problem and so does your suggestion of using a JOIN instead of a subselect.
-----Original Message----- From: Robert DiFalco [mailto:[EMAIL PROTECTED] Sent: Tuesday, October 10, 2006 8:54 AM To: Baron Schwartz; Rick James Cc: mysql@lists.mysql.com; [EMAIL PROTECTED] Subject: RE: Innodb Locks We'll do some testing with innodb_locks_unsafe_for_binlog but if this fixes the problem then it is a pretty safe assumption that the problem also exists with subqueries in DELETE and UPDATE and not just for that one case of INSERT as the article points out. -----Original Message----- From: Baron Schwartz [mailto:[EMAIL PROTECTED] Sent: Tuesday, October 03, 2006 1:39 PM To: Rick James Cc: Robert DiFalco; mysql@lists.mysql.com; [EMAIL PROTECTED] Subject: Re: Innodb Locks There is a detailed write-up on how locking works in the manual: http://dev.mysql.com/doc/refman/5.0/en/innodb-transaction-model.html If you are not doing replication, you might check out innodb_locks_unsafe_for_binlog as mentioned in http://dev.mysql.com/doc/refman/5.0/en/innodb-parameters.html. Peter Z also wrote an article on this: http://www.mysqlperformanceblog.com/category/replication/ You may get better performance from using a JOIN instead of an IN() subquery. You will have to test. Sometimes it is much better, sometimes worse. Usually better in my experience. Making the long-running query as short as possible is probably a good idea. Maybe you can break it up into several queries so it doesn't try to lock so many rows at once. There could be many other approaches too, it just depends on your needs and data. Without altering how locks are handled with startup options, the temporary table approach will avoid the locks only if you COMMIT after the CREATE... SELECT. The other subquery approach will not avoid them. I'm not sure if I should be replying to both the 'internals' and 'lists' mailing lists, since this was cross-posted. Feel free to give me guidance :-) Baron Rick James wrote: > Can't answer your question directly. But I wonder if this would trick > it into avoiding the lock: > > UPDATE AnotherTable > SET... > WHERE id IN (SELECT id FROM SomeTable); > > And the real workaround would be > > CREATE TEMPORARY TABLE t > SELECT id ...; > UPDATE AnotherTable > SET... > WHERE id IN (SELECT id FROM t); > >> -----Original Message----- >> From: Robert DiFalco [mailto:[EMAIL PROTECTED] >> Sent: Tuesday, October 03, 2006 9:26 AM >> To: mysql@lists.mysql.com; [EMAIL PROTECTED] >> Subject: RE: Innodb Locks >> >> Any thoughts on this? Should SomeTable be locked when performing the >> UPDATE on AnotherTable? >> >> ------- >> >> Is there a detailed source for when innodb creates row or table locks? >> >> I have a situation where one thread is performing this in one >> transaction: >> >> UPDATE SomeTable SET .... WHERE SomeTable.id = N; >> >> >> This is invoked after another thread has kicked off this long running >> query in another transaction: >> >> UPDATE AnotherTable >> SET ... >> WHERE EXISTS( >> SELECT null >> FROM SomeTable >> WHERE SomeTable.id = AnotherTable.id ); >> >> >> Would this create a conflicting lock? I am getting "Lock wait timeout >> exceeded" on SomeTable fro the UPDATE to SomeTable. >> >> TIA, >> >> R. >> >> >> -- >> MySQL General Mailing List >> For list archives: http://lists.mysql.com/mysql To unsubscribe: >> http://lists.mysql.com/[EMAIL PROTECTED] >> >> >> >> >> -- >> MySQL Internals Mailing List >> For list archives: http://lists.mysql.com/internals >> To unsubscribe: >> http://lists.mysql.com/[EMAIL PROTECTED] >> >> >> > > -- Baron Schwartz http://www.xaprb.com/ -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
