… people link to an INFORMATION_SCHEMA query to be able to find any indexes that have low cardinality, in an effort to find out what indexes should be… have to filter down to for an index to be useful (that is, eliminate 70-80% of rows). It’s not quite correct to quote… case, MySQL flipped from tablescan to index at about 34%. How am I supposed to find unused indexes then? You really have to run queries against your server…
Post: Dropping unused indexes
January 15, 2009 By 6 Comments
… time ago about how to find unused indexes with single query. I was working on the system today and found hundreds of unused indexes on dozens of tables so just dropping indexes manually did not look fun. So I extended Vadim’s query to generate…
Post: Advanced index analysis with mk-index-usage
November 11, 2010 By 2 Comments
…index-usage to help you determine how indexes are used in more flexible ways. The default report just prints out ALTER statements for removing unused indexes… the SSH tunnel to query EXPLAIN and find out the index usage on…_post_id = ? and comment_type not regexp ? and comment_approved = ? sample: …
Post: Finding out largest tables on MySQL Server
February 4, 2008 By 24 Comments
…to Information Schema but I still wanted to post little query I use for the purpose so I can easily find…indexes (so it is well possible there are some duplicates, redundant or simply unused indexes…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
…unusable. To be honest I do not really like averages Innodb provides as it is hard to get average for interval you want to…to look at the log files to find…index lookups which is indication of hash index efficiency. There is currently not much you can do to adjust adaptive hash index…
Comment: Unused indexes by single query
September 14, 2008 By 14 Comments
… shouldn’t simply drop the unused indexes. This patch, like any patch, should probably only… It is always safer to leave an index than drop it. If an index is not DEFINITELY causing a problem… leave it. If you want to drop an index, do some performance testing to find out how much benefit (disc space,…
Post: Economics of Performance Optimization
March 13, 2008 By 9 Comments
…indexes is not that hard to do. At the same time it may make sense to attract experts to review what you’re doing to…find them in the situation when they have hard time allocating resources to get application optimized properly – they need to…
Post: Give me 8 hours, and I'll help you build a better application
August 29, 2009 By 4 Comments
… wants to know how to deal with an application that is growing. The simplest way is to …to keep in memory to function well. That’s because unused rows can bloat and dilute your indexes …not be telling you when the service is down. Be the first to know, and have enough information to help you find…
