I recently worked on upgrading MySQL from one of very early MySQL 5.0 versions to Percona Server 5.1. This was a classical upgrade scenario which can cause surprises. Master and few slaves need to be upgraded. It is a shared database used by tons of applications written by many people over more than 5 years [...]
Upgrading MySQL
January 5, 2010 By 23 Comments
Upgrading MySQL Server is a very interesting task as you can approach it with so much different “depth”. For some this is 15 minutes job for others it is many month projects. Why is that ? Performing MySQL upgrade two things should normally worry you. It is Regressions – functionality regressions when what you’ve been [...]
table_cache negative scalability
November 16, 2009 By 23 Comments
Couple of months ago there was a post by FreshBooks on getting great performance improvements by lowering table_cache variable. So I decided to investigate what is really happening here. The “common sense” approach to tuning caches is to get them as large as you can if you have enough resources (such as memory). With MySQL [...]
Copying InnoDB tables between servers
July 31, 2009 By 11 Comments
The feature I announced some time ago http://www.mysqlperformanceblog.com/2009/06/08/impossible-possible-moving-innodb-tables-between-servers/ is now available in our latest releases of XtraBackup 0.8.1 and XtraDB-6. Now I am going to show how to use it (the video will be also available on percona.tv). Let’s take tpcc schema and running standard MySQL ® 5.0.83, and assume we want to copy order_line [...]
Crashes while using MyISAM with multiple key caches
July 18, 2009 By Leave a Comment
Over last couple of years I have ran into random MySQL crashes in production when multiple key caches were used. Unfortunately this never was frequent or critical enough issue so I could spend time creating repeatable test case and search of the bug in the MySQL database did not find anything. Recently we had this [...]
Pretending to fix broken group commit
February 2, 2009 By 11 Comments
The problem with broken group commit was discusses many times, bug report was reported 3.5Â years ago and still not fixed in MySQLÂ 5.0/5.1 (and most likely will not be in MySQLÂ 5.1). Although the rough truth is this bug is very hard (if possible) to fix properly. In short words if you enable replication (log-bin) on server [...]
High-Performance Click Analysis with MySQL
December 22, 2008 By 13 Comments
We have a lot of customers who do click analysis, site analytics, search engine marketing, online advertising, user behavior analysis, and many similar types of work. The first thing these have in common is that they’re generally some kind of loggable event. The next characteristic of a lot of these systems (real or planned) is [...]
Can MySQL temporary tables be made safe for statement-based replication?
May 26, 2008 By 8 Comments
A while ago I wrote about how to make MySQL replication reliable, part of which is to eliminate temporary tables. The idea is this: if a slave is stopped (or crashed) while a temporary table is open and is then restarted, the temporary table doesn’t exist anymore, and the slave will have problems trying to [...]
Updated msl (microslow) patch, installation walk-through!
April 20, 2008 By 17 Comments
For a couple of months there have been no updates to our msl patch, however recently I managed some time to change this. The functionality was extended a little bit and what’s even more important the patch is available for all the recent MySQL releases. To remind anyone who has not yet come across this [...]
TPC-H Run on MySQL 5.1 and 6.0
April 10, 2008 By 16 Comments
We were doing MySQL Performance evaluation on TPC-H queries for the client and they kindly allowed us to publish results which are very interesting. This is obviously not audited TPC-H run, and it can’t be because we used MyISAM tables which are not ACID complaint. Plus we only measured Power to keep things simple. We [...]
