… InnoDB table statistics is used for JOIN optimizations and helping the MySQL optimizer choose the appropriate index for a query. If a table’s statistics or index…
Post: When Does InnoDB Update Table Statistics? (And When It Can Bite)
October 6, 2011 By 5 Comments
Post: Statistics of InnoDB tables and indexes available in xtrabackup
September 14, 2009 By 6 Comments
… be quite inaccurate as secondary indexes tend to take more space. So we added more detailed index statistics into our xtrabackup utility. The… the post – if you are badly missing some features in MySQL, InnoDB, InnoDB-plugin, XtraDB, XtraBackup – you know whom ask for!
Post: Beware the Innodb Table Monitor
November 29, 2011 By 2 Comments
… Innodb Table Monitor has existed for basically forever in Innodb (the MySQL …Innodb really did have all the indexes or not. I collected the data just fine, and I found that indeed the indexes that Innodb…innodb_plugin/dict/dict0dict.c: line 4883 So, the io-wait spike is explained by table statistics…
Post: The new cool MySQL patch has landed! Check your queries performance!
October 31, 2007 By 16 Comments
…. Full_join means any of the joins didn’t use indexes. If a temporary table is required for query execution Tmp… temporary files. INNODB USAGE The final part are the InnoDB usage statistics. MySQL currently allows you to see many per-session statistics for operations with…: No # Filesort: No Disk_filesort: No Merge_passes: 0 # No InnoDB statistics available for this query SELECT COUNT(1) FROM t2; Important…
Post: MySQL Binaries Percona build10
December 11, 2008 By 12 Comments
…InnoDB scan | 1.0 | Percona | GPL | The names are Innodb_scan_* | | userstatsv2.patch | SHOW USER/TABLE/INDEX statistics | V2 | Google | GPL | Added INFORMATION_SCHEMA.*_STATISTICS…
Post: ANALYZE: MyISAM vs Innodb
September 3, 2008 By 9 Comments
…_innodb type=innodb; Query OK, 245760 rows affected, 1 warning (51.87 sec) Records: 245760 Duplicates: 0 Warnings: 0 mysql> show index from antest_innodb… statistics comes from NULL handling. MyISAM has a special variable which controls if NULLs should be considered equal when computing stats: mysql…
Post: Why InnoDB index cardinality varies strangely
September 28, 2009 By 5 Comments
… I started to look into something interesting with the index cardinality statistics reported by InnoDB tables. The cardinality varies because it’s derived… on MySQL 5.0.45 and put them into a file: baron@kanga:~$ while true; do mysql sakila -N -e ‘show index from… the others; it looks like the random choice of which statistic to use is not evenly distributed. I mentioned this to…
Post: Percona Server 5.1.55-12.6
March 7, 2011 By 5 Comments
…_READ columns of TABLE_STATISTICS and INDEX_STATISTICS were not properly updated when a query involved index lookups on an InnoDB table. (Yasufumi Kinoshita) Bug… or removing an index even on an empty InnoDB table could take a long time due to excessive locking when innodb_dict_size…
Post: Troubleshooting MySQL Upgrade Performance Regressions
February 15, 2012 By Leave a Comment
… hints such as STRAIGHT_JOIN, FORCE INDEX, BIG_RESULT/SMALL_RESULT. Check whatever…ANALYZE TABLE on both MySQL Versions to see if you can get statistics to be …innodb_stats_on_metadata and increasing innodb-stats-sample-pages to get more accurate results. In recent Percona Server versions and MySQL…
Post: Percona Server and XtraBackup weekly news, February 5th
February 6, 2011 By 2 Comments
… about making innodb_file_per_table a session variable. There was discussion on a bug that makes the INDEX_STATISTICS and TABLE_STATISTICS tables… at all. Mark Callaghan found a bug in INFORMATION_SCHEMA.INNODB_SYS_TABLES in the 5.1 server code. Percona XtraBackup… discussed for innobackupex. There was discussion about making tar4ibd support InnoDB‘s compressed tables.
