… already discussed 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 “keycache…
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 … 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 be so much more helpful if you could use multiple key caches for the same table, for example caching even/odd key…
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 and… is comparison of MyISAM Innodb and Falcon results in the graphical form: I’ve created bug, for MyISAM key cache contention issue and lets…
Post: Getting annoyed with MyISAM multiple key caches.
May 1, 2009 By 11 Comments
… wrote few times using multiple key caches is a great way to get CPU scalability if you’re using MyISAM. It is however very annoying – this feature really looks half baked to me. The problem with multiple key caches and mapping… how relevant is MyISAM with MariaDB on a way but this is surely sad to see the feature of multiple key caches first introduced…
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 27 Comments
… key buffer, key_buffer, and key cache interchangeably. However, I will be careful about the difference between “rate” and “ratio”. In this article, the key cache… to do a Key_read as a Key_read_request, what use would the key buffer be anyway? Let’s trust MyISAM‘s creators… possibility of having multiple key caches. But I’ll give the simple version here. In my opinion, you should choose a key_buffer_size…
Post: Crashes while using MyISAM with multiple key caches
July 18, 2009 By Leave a Comment
… related to multiple key caches but to online key cache resize. It is just this code most actively used in case you’re using multiple key caches. It is very rare one would resize single key cache in production and it only triggers… less than 1% of people would resize key cache while server is up or use multiple key caches. The fix of it is not easy…
Post: Using MyISAM in production
June 17, 2006 By 35 Comments
… you have decent myisam_sort_buffer_size and large myisam_max_sort_file_size otherwise recovery may be done by key_cache rather than sort which can take even longer. Be careful with myisam_recover. This is great… problems reside. Cache/Session tables (you can throw them away if it server crashes). You can use multiple of cache tables to avoid…
Post: MySQL Crash Recovery
July 30, 2006 By 26 Comments
… file nasty things may happen, not to mention such potentially multiple operation DDL statements as RENAME TABLE – these are most vulnerable… 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…
Post: MySQL MyISAM Active Active Clustering - looking for trouble ?
March 15, 2007 By 4 Comments
…MyISAM tables if you follow certain rules like enabling external locking, disabling query cache and delayed key…overhead you get from external locking. Plus key cache have to be invalidated with remote …than IO subsystem it may sense configure multiple MySQL servers this way. High availability ? …
Post: Cache Performance Comparison
August 9, 2006 By 73 Comments
… have multiple layer of caching and then same data may be stored in OS file cache, than SAN Cache you may implement multiple levels of caching… KEY (`k`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; INSERT INTO `test` VALUES (‘test’,'MyTestString’); 3) You need all caches to work, ie query cache enabled…
