…check which sessions have created which temporary tables (both in memory and not): mysql> select * from information_schema.global_temporary_tables…
Post: Best kept MySQLDump Secret
March 23, 2012 By 11 Comments
…use this technique ? The problem comes from the fact how MySQL‘s Transactions work with DDL, In particular ALTER TABLE. When ALTER TABLE…a pretty edge case scenario neither the less it can be problem for some workloads which run ALTER TABLE…
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
… talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. We are taking a look at and benchmarking optimizer… (ICP). Its available in both MySQL 5.6 and MariaDB 5.5 Now let’s take a look briefly at what this… the part on which range condition is applied cannot be used for filtering records. For example, suppose you have a key defined as…
Comment: Should you move from MyISAM to Innodb ?
March 10, 2012 By 53 Comments
… MySQL community are snobbish about using MyISAM (not using it that is) and that if not using InnoDB you aren’t too smart. However, InnoDB brings a lot of cons to the table which are…are other engines better than InnoDB for certain usage patterns – if you go down this path check them…
Post: Troubleshooting MySQL Upgrade Performance Regressions
February 15, 2012 By Leave a Comment
…MySQL Sandbox) can especially be helpful. Once you have spotted the query which performs differently between MySQL Server versions you should: Check…engines it is possible for stats to be different for the same data because it uses…
Post: How to Monitor MySQL with Percona's Nagios Plugins
February 22, 2012 By 8 Comments
…a database isn’t owned by MySQL, you won’t have any problems until you try to create or drop a table…engine. For example, a pile-up of connections all trying to open or close tables…which can give the system administrator time to address the situation before it becomes a problem. This check…
Post: Should we give a MySQL Query Cache a second chance ?
April 10, 2011 By 63 Comments
…table. Instead we could track versions for tables (increment each time table is updated) and check whenever version matches for all tables on which…useful for complex expensive queries, for which tracking exact rows used from query syntax may be hard. Query Cache Storage Engines MySQL…
Post: MySQL opening .frm even when table is in table definition cache
November 21, 2011 By 8 Comments
… instead of the normal binary format FRM. some legacy check for a generic table type (I think, I haven’t gone back into… is used is that in the DROP TABLE code path, MySQL uses this magic byte to work out which Storage Engine to ask to drop the table. The main consequence of this bit of code is that MySQL may cause…
Post: Using VIEW to reduce number of tables used
September 28, 2007 By 12 Comments
…CHECK OPTION failed ‘test.post123′ This happens because as we do not pass user_id value to underlying table MySQL…tables as blackhole and define a triggers on them to update base tables, which will make rows available in the views. As the storage engine…
Post: How to recover deleted rows from an InnoDB Tablespace
February 20, 2012 By 3 Comments
…tables and indexes (with their IDs) to the error log. mysql (employees) > CREATE TABLE innodb_table_monitor (id int) ENGINE=InnoDB; TABLE…mysql-data-recovery:generating_a_table_definition With the table definition on table…
