… be 100 disk seeks to answer a random query, assuming you can get each index query down to one disk seek.) I claim… advantages of the newer version of iiBench (the python version that Mark wrote http://bazaar.launchpad.net/~mdcallag/mysql-patch/mytools/annotate/head%3A/bench/ibench/iibench.py) is that it measures query performance too, so…
Comment: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 22, 2012 By 10 Comments
Thanks for interesting results! The variation in query execution plans is probably a result of variation in InnoDB … can do about that. In MySQL 5.6 you can use InnoDB Persistent Statistics to get stable statistics and plan stability. (See… versions by increasing the amount of sampling used to compute the statistics. (See http://oysteing.blogspot.com/2011/04/more-stable-query…
Post: MySQL Slow query log in the table
May 31, 2007 By Leave a Comment
… of MySQL 5.1 get MySQL slow query log logged in mysql.slow_log table instead of the file as you had in previous versions. We rarely would use this feature as it is incompatible with our slow query analyses patch and… in MySQL is well though of in regards to avoiding trouble. For example you can’t ALTER log table while query is…
Post: Troubleshooting MySQL Upgrade Performance Regressions
February 15, 2012 By Leave a Comment
… MySQL version. Once you have the queries you will most likely able to repeat the problem by running query on old and new MySQL Server version… standpoint and updating stats may cause old MySQL Version to get slower plan instead of new one getting faster. Check stats sampling settings such…
Post: Upgrading MySQL
January 5, 2010 By 23 Comments
… just for this project. Query Validation It is often hard to ensure queries work same way with different MySQL version, unless you have very detailed automated QA. So what you can do is get the backup of the database and get query…
Post: Should we give a MySQL Query Cache a second chance ?
April 10, 2011 By 63 Comments
… version matches for all tables on which query depends on. If not you need to re-generate the query result. Removing of stale queries… than wire speed for 1Gb networks. Plus if we can get MySQL protocol to support such light compression in addition to zlib…. Improve Manageability What is in the MySQL Query Cache ? How many hits did we get for this query item ? Right now none of such…
Post: Slow Query Log analyzes tools
September 6, 2006 By 83 Comments
… long_query_time=0 This patch is adapted version of patch by Georg Richter which was made to run with recent MySQL version. Now why do not we use general log instead ? Unfortunately general logs queries before queries are executed (and… you query log and get back to unpatched version. It is best if you generate this log for all your queries with long_query_time…
Post: Shard-Query EC2 images available
May 11, 2011 By 2 Comments
…mysql> use ontime1; Database changed mysql> show table status like ‘ontime_fact’G *************************** 1. row *************************** Name: ontime_fact Engine: InnoDB Version…
Post: The story of one MySQL Upgrade
October 8, 2010 By 8 Comments
I recently worked on upgrading MySQL from one of very early MySQL 5.0 versions to Percona Server 5.1. This was a… the same position again and used tcpdump and mk-query-digest to get sample read traffic from both master and slave. –sample… with New MySQL version upgrade involves new Operating System and hardware and any of them could be potential cause of rollback. MySQL Upgrade…
Post: 10+ Ways to Crash or Overload MySQL
November 13, 2007 By 20 Comments
…. General Overload As MySQL does not have much of resource utilization control you can simply run heavy queries to get MySQL Server barely functional. The limits which exist are not really helpful as they do not define query complexity… old MySQL versions which typically have more issues. P.P.S Nothing I write here is security hole which is unknown to MySQL…
