Group commit and XA
Posted by Vadim |
Returning to post Group commit and real fsync I made several experiments:
I ran sysbench update_key benchmarks without —log-bin, with —log-bin, and with —log-bin and —innodb-support-xa=0 (default value is 1). Results (in transactions / sec)
| threads | without —log-bin | —log-bin | —log-bin and —innodb_support-xa=0 |
| 1 | 1218.68 | 614.94 | 1010.44 |
| 4 | 2686.36 | 667.77 | 1162.60 |
| 16 | 3993.59 | 666.14 | 1161.56 |
| 64 | 3630.55 | 665.18 | 1151.36 |
So we can see group commit is not only broken when XA is enabled but also if XA is disabled but binary log is enabled. Performance without XA can be twice as good as with XA if binary logs are enabled as Innodb will need to flush its log buffer only once. So, if you are using —log-bin with innodb tables it makes sense to set —innodb-support-xa=0
Posted by Vadim @ 12:59 pm :: Innodb, bugs
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3 Comments
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- MySQL Performance Blog » Blog Archive » Jeremy Cole on MySQL Replication
[...] Watch out for MySQL 5.0 - if you enabled Binary log with MySQL 5.0 you loose group commit which can dramatically increase commit rate for multiple user load. See this post by Vadim for benchmark results. [...] - MySQL Performance Blog » MySQL 4 to MySQL 5 Upgrade performance regressions
[...] problem in both cases was MySQL 5.0 broken group commit [...] - Heikki Tuuri Innodb answers - Part I | MySQL Performance Blog
[...] PZ: You can disable binary logging to get Group Commit back. Though this is often not the option. Here are some benchmarks we did. [...] - Pretending to fix broken group commit | MySQL Performance Blog
[...] it before, see http://www.mysqlperformanceblog.com/2006/05/03/group-commit-and-real-fsync/ and http://www.mysqlperformanceblog.com/2006/05/19/group-commit-and-xa/ The problem is the InnoDB tries to keep the same order of transactions in binary logs and in [...] - DeShong.net » MySQL replication and the sync_binlog option
[...] read a bit more about in Jeremy Cole’s post on MySQL replication. You can also see some handy benchmarks that compare MySQL with and without binary [...]
Hi,
What version of 4.1 did group commit first show up in?
Thanks,
Mike
Comment :: June 10, 2007 @ 8:25 am
Hello,
Please, what means “XA” ?
I cannot find the meaning on the web.
Regards
Jonatas
Comment :: September 13, 2007 @ 6:02 am
Jonatas,
http://en.wikipedia.org/wiki/X/Open_XA
Comment :: September 13, 2007 @ 8:34 am