… | id | select_type | table | type | possible_…| 4 | const | 1 | Using filesort | | 1 | SIMPLE | LinksTbl2 | index_merge | tstamp,userid,converted_from_id,item_desc,…
Post: Announcement of Percona XtraDB Cluster 5.5.23
May 14, 2012 By 11 Comments
…. List of changes: Fixes merged from upstream (Codership-mysql) Support for MyISAM, now changes to MyISAM tables are replicated to other nodes…
Post: Percona welcomes Drizzle 7.1
April 10, 2012 By Leave a Comment
… API (experimental) Some of the Percona InnoDB patches have been merged Since Drizzle 7.0 (which was released last year), there… include: authentication via PAM, authentication via HTTP, various DATA_DICTIONARY tables, the Drizzle protocol plugin, authentication from a file, MySQL UNIX socket protocol, javascript plugin, authentication via tables (similar to MySQL), RabbitMQ, regex policy, logging to syslog, authentication…
Post: AUTO_INCREMENT and MERGE TABLES
September 11, 2008 By Leave a Comment
…> truncate table a2; ERROR 1105 (HY000): MyISAM table ‘a2′ is in use (most likely by a MERGE table). Try FLUSH TABLES. mysql> flush tables; Query OK… careful while running ALTER TABLE for underlying tables. Unlike with TRUNCATE TABLE there is no warning displayed but the MERGE TABLE may continue having old…
Post: Merge Tables Gotcha
May 9, 2007 By 4 Comments
… NULL for the merge table: “create table tx (id int unsigned, key(id)) type=merge union(t1,t2)” If you create table this way it… underlying MyISAM tables, but not in the MERGE table. There it is indexed but not as a PRIMARY KEY because a MERGE table cannot enforce uniqueness over the set of underlying tables…
Post: Multi Column indexes vs Index Merge
September 19, 2009 By 30 Comments
… | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +—-+————-+———+————-+—————-+——-+———+——+——+————————————-+ | 1 | SIMPLE | idxtest | index_merge | i1,i2,combined | i2… | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +—-+————-+———+————-+—————-+——-+———+——+——–+————————————–+ | 1 | SIMPLE | idxtest | index_merge | i1,i2,combined | i1…
Post: Possible optimization for sort_merge and UNION ORDER BY LIMIT
September 18, 2007 By 10 Comments
… optimization impossible, not even speaking about index merge optimization. Lets look at this example: CREATE TABLE `utest` ( `c1` int(10) unsigned NOT… \G *************************** 1. row *************************** id: 1 select_type: SIMPLE table: utest type: index_merge possible_keys: c1,c2 key: c1,c2 key_len…
Post: 10+ Ways to Crash or Overload MySQL
November 13, 2007 By 20 Comments
…-8K per table though complex tables can require larger sizes, so this is mainly the problem for smaller servers. Table Cache Merge Tables – Table Cache is… descriptors. This is not the case with Merge tables for example – creating and accessing few merge tables with 1000 of subtables will likely cause…
Comment: MySQL Installation and upgrade scripts.
May 21, 2007 By 3 Comments
… “check for upgrade” repairs, no problems with large merge tables (Unable to open underlying table which is differently defined or of non-MyISAM… – slow, with “check for upgrade” repairs, problems with merge tables, performance problems while table is updated by PK = empty string (actially is was…
Comment: Merge Tables Gotcha
March 26, 2008 By 4 Comments
i have a strange problem with merge table. i create 5 tables from the same create statement and merge table on them. indexes cardinality equals none. when i alter the merge table and leave only any 4 tables (in the union) index cardinality becomes a number.
