… MyISAM tables? MyISAM have not been getting any significant development since MySQL 4.1, so in-place upgrade of MySQL 5.0 to MySQL…plan either by updating statistics (ANALYZE TABLE) or disabling some of the optimization/statistics related features in new version. Innodb statistics can especially be…
Post: ANALYZE: MyISAM vs Innodb
September 3, 2008 By 9 Comments
… the statistics comes from NULL handling. MyISAM has a special variable which controls if NULLs should be considered equal when computing stats: mysql…: mysql> update antest set c=NULL; Query OK, 245760 rows affected (11.48 sec) Rows matched: 245760 Changed: 245760 Warnings: 0 mysql> update antest…
Post: Troubleshooting MySQL Upgrade Performance Regressions
February 15, 2012 By Leave a Comment
… Run ANALYZE TABLE on both MySQL Versions to see if you can get statistics to be same or …wrong plan from optimizer standpoint and updating stats may cause old MySQL Version to get slower plan … sampling settings such as innodb-stats-method and myisam-stats-method. For Innodb storage engines it is…
Post: Using MyISAM in production
June 17, 2006 By 36 Comments
…MyISAM storage engine. This hidden corruption may later cause crashes wrong query results and further data corruption. Partial updates. MyISAM…MySQL treats updates as higher priority operations. You can use SELECT HIGH_PRIORITY or UPDATE… always available. For example statistical data. Data on slave …
Post: MySQL Server Variables - SQL layer or Storage Engine specific.
June 8, 2006 By 14 Comments
…MyISAM variables are not important ? Not really. You still have some tables in MyISAM format in “mysql” … low_priority_updates If enabled selects will get higher priority than updates and waiting update will …for all storage engines. timed_mutexes Show statistics by mutexes in SHOW MUTEX STATUS. Was…
Post: Using Multiple Key Caches for MyISAM Scalability
November 26, 2008 By 8 Comments
… written before – MyISAM Does Not Scale, or it does quite well – two…table usage I will use Percona Patches: mysql> select * from information_schema.table_statistics where table_schema=’test’ and … rows modified and updated but you can surely use different formula if you like. mysql> select t.table_…
Post: MySQL optimizer: ANALYZE TABLE and Waiting for table flush
February 27, 2013 By 3 Comments
…update-table-statistics-and-when-it-can-bite/ There are some variables to tune how that statistics… query we run ANALYZE TABLE: mysql> analyze table t; +——–+———+———-+———-+ | Table | Op | Msg_type | Msg_… is MyISAM there will be no rollback process so all the already updated …
Post: MySQL Crash Recovery
July 30, 2006 By 30 Comments
… may seriously affect MySQL Performance. MyISAM Corruption – If you’re writting to MyISAM tables there… mention MyISAM tables can contain partially completed statements as well as some of updates … longer time on extreme load. Innodb statistics – Unlike MyISAM Innodb does not store index cardinality …
Post: Updated msl (microslow) patch, installation walk-through!
April 20, 2008 By 17 Comments
… have been no updates to our msl patch, however…mysql-5.0.51a/ mysql-5.0.51a/bdb/ mysql-5.0.51a/bdb/Makefile.in mysql-5.0.51a/bdb/btree/ mysql… significantly longer to close than MyISAM), database configuration, load, etc. …details and InnoDB engine per-query statistics. With this option you may…
Post: MySQL EXPLAIN limits and errors.
July 24, 2006 By 6 Comments
… lieing you you can use SHOW STATUS “Handler” statistics to see if number of operations match. EXPLAIN … you full story, especially now as MySQL has triggers which can make updates very different. Also there is …key_cache as it can for MyISAM. EXPLAIN may take long time In MySQL 5.0 with addition of …
