…, looking_for, location; integer – age 3) All queries fall into X IN (…) AND Y IN …use either indexes built on multiple columns or intersection of multiple accesses by indexes. When we talk about index_merge…can choose between two which is more selective. 3) You can even use (City, Gender, Age, …
Post: New patches, new builds
September 5, 2008 By 24 Comments
…separated releases of 5.0 into two branches. First, just “-percona” release …of IO threads control_flush_and_merge_and_read.patch | InnoDB patch …think InnoDB plugin is stable enough to use it with MySQL 5.1 RC…new column TIME_MS to INFORMATION_SCHEMA.PROCESSLIST which contains time of query execution …
Comment: MySQL Server Memory Usage
September 1, 2006 By 21 Comments
…’ve read Peter Z two guides but cannot really…’ ‘Com_show_collations’, ’176788′ ‘Com_show_column_types’, ’0′ ‘Com_show_create_db…’OFF’ ‘Slow_launch_threads’, ’0′ ‘Slow_queries‘, ’27405′ ‘Sort_merge_passes’, ’376′ ‘Sort_range’, ’56479689′ …MyISAM which isnt used. sort_buffer_size=2M query_cache_size=10M…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 141 Comments
…over 30 millions of rows. “val” column in this table has 10000 distinct…used to compose the complex object which was previously normalized to several tables or perform complex queries… can’t do hash join or sort merge join – it only can do … assume join would be close to two full table scans (as 60mil …
Comment: Multiple column index vs multiple indexes
August 25, 2008 By 13 Comments
Tgabi, The query you’re running is exactly query which can’t use multi column index completely – BETWEEN makes it to scan only first… you have query as you described the index should be (j,i) not (i,j) Now you also see two more things with your explain – first Index Merge is not really used here – it is just range…
