… MyISAM key cache has serious mutex contention issue as there is global mutex which is held for the time of key_block being copied from key_cache to the thread local space. Happily MyISAM allows you to create multiple key caches . We use…
Post: MyISAM Scalability and Innodb, Falcon Benchmarks
October 12, 2007 By 10 Comments
… on Key Read Request. This lock is per key cache so if you have contention while multiple indexes are used you can create multiple key caches… is comparison of MyISAM Innodb and Falcon results in the graphical form: I’ve created bug, for MyISAM key cache contention issue and lets see…
Post: Using Multiple Key Caches for MyISAM Scalability
November 26, 2008 By 8 Comments
I have written before – MyISAM Does Not Scale, or it does quite well – two main … held only when key block (1KB to 4KB) is being copied from Key Cache to thread local buffer, which is terrible contention spot in… also use multiple Key Caches to reduce or virtually eliminate key cache contention. Too bad you can only map single table to single key cache – it would…
Post: MySQL Crash Recovery
July 30, 2006 By 26 Comments
… log may become corrupted and out of sync with database content. This will sometimes break replication but if you’re just… caches. This may reduce performance dramatically. So if you’re bringing server back after crash you might want to populate caches. For MyISAM key_cache this can be done by using LOAD INDEX INTO CACHE statement, for other storage engines…
Comment: MyISAM Scalability and Innodb, Falcon Benchmarks
August 12, 2008 By 10 Comments
[...] thousands of context switches per second with far less work done than one would hope. As we already discussed MyISAM key cache has serious mutex contention issue as there is global mutex which is held for the [...]
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…key_buffer_sizeblogpercona.commanual key_cache_age_thresholdblogpercona.commanual key_cache_block_sizeblogpercona.commanual key_cache_division_limitblogpercona.commanual Key_read_requestsblogpercona.commanual Key_readsblogpercona.commanual Key_write_requestsblogpercona.commanual Key…
Comment: Using Multiple Key Caches for MyISAM Scalability
April 29, 2010 By 8 Comments
… wanted to post and confirm that smart use of multiple key caches for MyISAM tables can *dramatically* increase performance in high write applications… of MyISAM. It does not solve all the locking contention but if you have good table designs for your operational posture MyISAM can…
Post: What to do with MySQL Full Text Search while migrating to Innodb ?
September 10, 2009 By 12 Comments
… better data consistency guaranty or being bitten repairing multiple GB MyISAM table few times, though Table Locks is probably the most… time can be the problem, not to mention Key Cache which often becomes serious contention issue. The problem we often run into during… on secondary small tables which do not cause problems with contention or anything else. So this can be valid choice. Unfortunately…
Post: Cache Performance Comparison
August 9, 2006 By 73 Comments
… will be some syncronization contention while accessing shared memory cache which does not happen in this case. File cache really does great, even… KEY (`k`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; INSERT INTO `test` VALUES (‘test’,'MyTestString’); 3) You need all caches to work, ie query cache enabled…
Comment: Modeling InnoDB Scalability on Multi-Core Servers
January 28, 2011 By 11 Comments
On MyISAM – This is a very wrong benchmark for MyISAM Performance, It will use LOCK TABLES to “emulate” transactions. This … I would not expect MyISAM which is in MySQL 5.5 to scale very well because of key buffer contention, even if you would heave read only workload. The segmented key cache in MariaDB should help…
