… cause things breakage Table Locks – Table locks are not cleared until you fetch whole result set if you’re reading from tables directly (if you… do processing in PHP at all. Many summary tables can be built by INSERT … SELECT, or some others purely SQL commands and… time) or do INSERT … SELECT to the temporary table with auto_increment column and fetch data from this table using auto increment column…
Post: Thinking about running OPTIMIZE on your Innodb Table ? Stop!
December 9, 2010 By 18 Comments
… ) ENGINE=InnoDB AUTO_INCREMENT=12582913 DEFAULT CHARSET=latin1 mysql> select * from a order by id limit 10; +—-+——————————————+ | id | c | …from using LOCK TABLES on Innodb table to ensure there is not ton of queries starting reading table with no…
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
… | Waiting for table metadata lock | ALTER TABLE test_2 DROP COLUMN c | | 7 | msandbox | localhost | test | Query | 195 | Waiting for table metadata lock | select * from test_2 order by id | | 8 | msandbox | localhost | test | Query | 180 | Waiting for table metadata lock | select * from test…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…table_definition_cacheblogpercona.commanual table_lock_wait_timeoutblogpercona.commanual Table_locks_immediateblogpercona.commanual Table_locks_waitedblogpercona.commanual table_open_cacheblogpercona.commanual table…
Post: Paul McCullagh answers your questions about PBXT
November 20, 2009 By 2 Comments
… to be rebuilt, which can be done by REPAIR TABLE. The table data page size does not require a rebuild because… read locks. A normal SELECT does not lock at all. In addition, an UPDATE or DELETE only acquires a temporary row-lock. This lock is… of rows are selected in this manner. I should also mention that the consequence of this is that SELECT … LOCK IN SHARE MODE…
Post: Helgrinding MySQL with InnoDB for Synchronisation Errors, Fun and Profit
November 24, 2011 By 2 Comments
…by 0x6A87FC: handle_select(THD*, st_lex*, select_result*, unsigned long) (sql_select.cc:269) ==9090== by 0x63A3E3: execute_sqlcom_select(THD*, TABLE_LIST*) (… of error: lock order violation, thus a potential deadlock. The locks in question are LOCK_global_system_variables and LOCK_system_variables…
Post: Test Drive of Solid
September 22, 2006 By 5 Comments
…even if rows are locked or even modified unless you require locking read, in which case SELECT FOR UPDATE or SELECT … LOCK IN SHARE … what is really happening. Test 3: Phantom rows: Table before test: select * from test2; +—-+——–+ | id | names | +—-+——–+ | 1 | Mysql | | 2 | Solid | | …
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
… InnoDB 442 mysql tables in use 1, locked 0 MySQL thread id 8079, query id 728899 localhost root Sending data select sql_calc… of tables locked by transactions. Innodb does not lock tables for normal operation so number of tables locked normally stays 0, unless it is ALTER TABLE or similar statement, or if LOCK TABLES was…
Post: Percona XtraDB Cluster: Multi-node writing and Unexpected deadlocks
August 17, 2012 By 17 Comments
…TABLE LOCK table `test`.`autoinc` trx id 83B lock mode IX RECORD LOCKS space id 0 page no 823 n bits 72 index `PRIMARY` of table…1213 (40001): Deadlock found when trying to get lock; try restarting transaction node1 mysql> select * from autoinc; +—+——-+ | i | j | +—+——-+ | 1 | node3 | | 4…
Post: Using MyISAM in production
June 17, 2006 By 36 Comments
… MyISAM in production. For me it is not only about table locks. Table locks is only one of MyISAM limitations you need to consider… running select will also block further selects from this table – they will have to wait until UPDATE is executing which is waiting on SELECT… you enable this option – globally, for table or for set of statements (by using LOCK TABLES/UNLOCK TABLES) be careful. This option may improve…
