… packed rows – quite possible scenario for MyISAM tables. Now if we take the…MySQL can’t do hash join or sort merge join – it only can do nested loops method which requires a lot of index…index accesses – For large data sets full table scans are often faster than range scans and other types of index…
Post: Merge Tables Gotcha
May 9, 2007 By 4 Comments
… on the given column instead: mysql> create table tx (id int unsigned not null, key(id)) type=merge union(t1,t2); Query OK… in MySQL manual Here is what it says: Note that the a column is indexed as a PRIMARY KEY in the underlying MyISAM tables, but not in the MERGE table. There it is indexed but not…
Post: High-Performance Click Analysis with MySQL
December 22, 2008 By 13 Comments
… user behavior analysis, and many similar types of work. The first …are very expensive. If MySQL supported sort-merge or hash joins, you’d… huge MyISAM tables and taking downtime, I would not use MyISAM for …indexes less than half the size. In real life this technique often makes the table+index…
Post: Recovering Innodb table Corruption
July 4, 2008 By 22 Comments
…mysql> check table test; ERROR 2013 (HY000): Lost connection to MySQL server during query mysql> check table test; +———–+——-+———-+———-+ | Table | Op | Msg_type…MyISAM table you use for recovery after MySQL crashes to make sure indexes…, insert buffer merge or recovery from…
Comment: MySQL Partitioning - can save you or kill you
June 27, 2012 By 45 Comments
…MYISAM table, with a primary key consisting of 3 columns (ObjInstance (10000 types), objectClass (100 types) and timestamp of addition). All the 3 columns are also indexed…the tables below the merge table are queried. Also,… same time.. I know mysql should have no problem…
Comment: MySQL Server Memory Usage
September 1, 2006 By 21 Comments
…’, ’0′ ‘Com_create_index‘, ’0′ ‘Com_create_table’,…’ ‘Com_show_column_types‘, ’0′ ‘Com_…’Slow_queries’, ’27405′ ‘Sort_merge_passes’, ’376′ ‘Sort_range’,…mysql.sock pid-file=/var/run/mysql/mysql.pid datadir=/db/disk2/mysql/data log-bin=/var/log/mysql/log log-slow-queries=/var/log/mysql… for MyISAM which…
