The problem with broken group commit was discusses many times, bug report was reported 3.5Â … significantly. We wrote also about it before, see “Group commit and real fsync” and “Group commit and XA”. The problem is the InnoDB tries… current version for testing from Launchpad) we introduce –innodb-unsafe-group-commit mode. There are results with this options vs without (results…
Post: Group commit and real fsync
May 3, 2006 By 9 Comments
… looking at two issues here which interleave such funny way Group commit is broken in MySQL 5.0 if binary loging is enabled… 5.0 which did not work with former group commit code. The new code for group commit however was never implemented. XA allows to…. if binary log is disabled, so is XA and old group commit code works just fine. Second one is interesting. Actually we…
Post: Group commit and XA
May 19, 2006 By 8 Comments
Returning to post Group commit and real fsync I made several experiments: I ran sysbench ….55 665.18 1151.36 So we can see group commit is not only broken when XA is enabled but also if XA…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 17 Comments
… bad thrashing. Q22: Also, What’s the deal with group commit being broken in 5.1.x? Is it possible to get the… users, group commit being broken in 5.1 makes no difference. If you have a battery-backed disk controller cache, then the commit returns… users who had serve regressions in 5.0 because of group commit being broken. Most do not have RAID with BBU. With good…
Comment: Jeremy Cole on MySQL Replication
June 14, 2006 By 12 Comments
…, as you mentioned the issue of group commit being broken (see http://www.mysqlperformanceblog.com/2006/05/19/group-commit-and-xa), I read that…) enabled your benchmarks suggested that by doing that (even if group commit is “broken“) you can double your write throughput However, i stumbled…
Post: MySQL 4 to MySQL 5 Upgrade performance regressions
June 6, 2007 By 8 Comments
… code. The problem in both cases was MySQL 5.0 broken group commit bug. First I should note I am extremely unhappy how… you also have to have plenty of concurrent transactions so group commit would trigger in MySQL 4.0 and large number of… to get group commit back but obviously you loose point in time recovery and replication. Use innodb_flush_log_at_trx_commit=2…
Comment: When would you use SAN with MySQL ?
March 10, 2009 By 18 Comments
Peter, “MySQL also has broken group commit (which we have partial fix for) meaning concurrent transaction commits will need to be serialized.” I would… not grouped together, so there are many more physical I/O operations than if several transactions could be grouped into one commit. At least this is how I read the original group commit code from 4.x…
Comment: Jeremy Cole on MySQL Replication
June 14, 2006 By 12 Comments
… fsyncs. It is simple code which does not even have “group commit” allowing to flush several events with single write to disk… logging it however can do group commit, meaning it can commit several transactions which are waiting to be commited at the same time with single log write. This is currently broken in…
Comment: Testing the Group Commit Fix
July 13, 2011 By 13 Comments
…://www.mysqlperformanceblog.com/2009/02/02/pretending-to-fix-broken-group-commit/ Before the latest group commit fix turning on bin-log resulted in over… much performance drop does bin-log cause now with the group commit fix. 2) In your results did you use innodb_support…
Post: XtraDB storage engine release 1.0.2-3 (Spring edition) codename Sapporo
March 2, 2009 By 10 Comments
… read-write lock. See benchmark results. Fix broken group commit in InnoDB As you know, the group commit of InnoDB doesn’t work after MySQL…. We pretend to fix this and added “innodb_enable_unsafe_group_commit=[0|1]” parameter. Note if you set this parameter to…
