… large number of MySQL 5.0 and 5.1 installations that would upgrade or are in the process of upgrading to MySQL 5.5, I thought it…_text | +—-+——+————+ 1 row in set (0.00 sec) And you can see how isolation is broken because the SELECT was not repeatable… for the transaction to commit. For the reasons described above the implementation of Metadata Locking was changed, starting MySQL 5.5.3. Let’s…
Post: MySQL 4 to MySQL 5 Upgrade performance regressions
June 6, 2007 By 8 Comments
… just 5-10% you often see for simple queries due to generally fatter code. The problem in both cases was MySQL 5.0 broken group commit bug. First I should note I am extremely unhappy how MySQL handled this problem. While working for MySQL we… number of commits if you can. It is great optimization idea anyway. Also please do not read this post as MySQL 5.0 is…
Post: Group commit and real fsync
May 3, 2006 By 9 Comments
… months I’ve seen few cases of customers upgrading to MySQL 5.0 and having serious performance slow downs, up to 10 times… two issues here which interleave such funny way Group commit is broken in MySQL 5.0 if binary loging is enabled (as it enables XA… was implemented in MySQL 5.0 which did not work with former group commit code. The new code for group commit however was never implemented…
Post: XtraDB storage engine release 1.0.2-3 (Spring edition) codename Sapporo
March 2, 2009 By 10 Comments
… announce release 1.0.2-3 of our XtraDB storage engine. Here is a list of enhancements: Move to MySQL 5.1.31… benchmark results. Fix broken group commit in InnoDB As you know, the group commit of InnoDB doesn’t work after MySQL 5.0 with binlog. We pretend to fix this and added “innodb_enable_unsafe_group_commit=[0…
Post: Announcing Percona Server 5.5.27-29.0
October 11, 2012 By Leave a Comment
… Server 5.5.27-29.0 on October 11th, 2012 (Downloads are available here and from the Percona Software Repositories). Based on MySQL 5.5.27, including all the bug fixes in it, Percona Server 5.5.27-29.0 is now the current stable release in the 5.5… III). Option expire_logs_days was broken by group_commit patch introduced in Percona Server 5.5.18-23.0. Bug fixed #1006214 (Stewart Smith…
Comment: Jeremy Cole on MySQL Replication
June 14, 2006 By 12 Comments
… mentioned the issue of group commit being broken (see http://www.mysqlperformanceblog.com/2006/05/19/group-commit-and-xa), I read that… (even if group commit is “broken“) you can double your write throughput However, i stumbled upon this in the official mySQL 5.0 documentation: “Even… binary log. (Note: –innodb-safe-binlog is unneeded as of MySQL 5.0; it was made obsolete by the introduction of XA transaction…
Post: How much overhead DRDB could cause ?
June 2, 2008 By 4 Comments
…_flush_log_at_trx_commit=1 and sync_binlog=1 you will have 4 “sync” operations in MySQL 5.0 – there is event written to the binary log to “prepare” XA transaction, when there is record in Innodb log to commit… are fully serialized because group commit in Innodb was broken in 5.0 and it is still not fixed in 5.1 to date. So…
Comment: Jeremy Cole on MySQL Replication
June 14, 2006 By 12 Comments
… log writes. In MySQL 4.1 and MySQL 5.0 without binary 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 5.0…
Post: Watch out for Marketing benchmarks
August 23, 2006 By 7 Comments
… vs 5.0 benchmarks which were done only benchmarks which show MySQL 5.0 is faster were selected and bunch of other benchmarks which show 5.0… before MySQL 5.0 was stable but were not fixed, others, such as broken group commit could have been handled better. Same applies to comparing MySQL…
Comment: Group commit and real fsync
November 20, 2007 By 9 Comments
[...] originally performed InnoDB scalability tests for MySQL 5.0 to show broken group commit [...]
