…_multi_range_next,QUICK_RANGE_SELECT::get _next,rr_quick,sub_select,do_select,JOIN::exec,mysql_select,handle_select,execute_sqlcom_select,mysql_execute_command,my sql_parse…_range_next,QUICK_RANGE_SELECT::get_next,rr_quick,sub_select,do_select,JOIN::exec,mysql_select,handle_select,execu te_sqlcom_select,mysql_execute_command,mysql_parse,dispatch_command…
Post: Upgrading MySQL
January 5, 2010 By 23 Comments
… previously sub second. The changes which got a lot of publicity over years is change of TIMESTAMP output format in MySQL 4… application which uses simple MySQL functionality which is unlikely to be affected. If you’re something like SELECT name FROM users WHERE… to run comparison. The tool will run SELECT queries on both new and old MySQL installations and check result set, explain plan…
Comment: ORDER BY ... LIMIT Performance Optimization
November 17, 2009 By 93 Comments
…mysql> show index from follow; +——–+————+———-+————–+————–+———–+————-+———-+——–+——+————+———+ | Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub… mysql> explain SELECT…
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 12 Comments
…) supports basic queries which use select/group by/join/where. You may not use sub-queries or any non-deterministic …than COUNT(*). mysql> select count(*) cnt from order_lines\G *************************** 1. row *************************** cnt: 155187034 1 row in set (32.03 sec) mysql> select sum(…
Post: Using any general purpose computer as a special purpose SIMD computer
May 16, 2011 By 6 Comments
… or dates can be transformed into one or more discrete sub-ranges Any operation on an entire set is the same… the serial version as run by the native database interface (MySQL): mysql> select word, md5(word), md5(reverse(word)), count(*) from words2 group…. Likely current network technologies can not support such a degree. mysql> select min(id),max(id) from words; +———+———+ | min(id) | max(id…
Post: Distributed Set Processing with Shard-Query
May 14, 2011 By 27 Comments
… non-distributable ones, can be broken into distributable sub-expressions. What is a result set? This …resource which speaks SQL, but right now only MySQL storage nodes are supported. Amdahl’s law …threshold of 128 items * The following projections were selected for a UNIQUE CHECK * on the base table:…
Post: ANALYZE: MyISAM vs Innodb
September 3, 2008 By 9 Comments
…mysql> select count(distinct c) from antest; +——————-+ | count(distinct c) | +——————-+ | 101 | +——————-+ 1 row in set (0.36 sec) mysql> select…
Comment: Sphinx: Going Beyond full text search
July 26, 2007 By 18 Comments
… ON CASCADE DELETE, sub varchar REFERENCES subdomains ON CASCADE DELETE, ); CREATE INDEX paths(sub, domain, port, path); SELECT proto || “://” || coalesce(sub || “.”, “”) || domain || coalesce(“:” || port, “”)|| path FROM paths WHERE domain=”mysql.com” AND path LIKE…
Comment: ORDER BY ... LIMIT Performance Optimization
December 29, 2008 By 93 Comments
…help me? In MySQL I do: > create…| Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | … explain select id from c limit 20000000,20; +—-+————-+——-+——-+—————+———+———+——+———-+————-+ | id | select_type |…
Post: Are you designing IO bound or CPU bound application ?
December 20, 2006 By 10 Comments
…boring and obvious but it is extremely important for MySQL Performance Optimization. In fact I probably have to …are updated (ie use triggers) and make sure all selects use index for ORDER BY .. LIMIT. For IO … would likely be much slower than (user_id,sub_id) combined primary key as this one will …
