… as if one of the places where Galera’s optimistic locking gets into trouble is large transactions that touch a lot of…, which is a lower bound. Any update that commits and gets into group communications from the time of the BEGIN on…
Comment: Percona XtraBackup 2.0.7 for MySQL available for download
May 14, 2013 By 1 Comment
… this software to 2.0.7. But my backup script get this error: “innobackupex: fatal error: no ‘innodb_buffer_pool_filename….168.10.118 –user=backup –password=23khfisF –slave-info –no-lock –safe-slave-backup /db/backup/tst_ch118_3/201305″ innodb…
Post: Innodb Table Locks
July 31, 2012 By 4 Comments
… (note – same table gets counted twice) in use but zero tables are locked. Innodb does not need any row locks for conventional selects… id 12304 lock_mode X When updating the table it also gets “locked“, now with IX lock… this is because update needs to lock the rows in exclusive mode. Similar to IS lock IX…
Post: Test Drive of Solid
September 22, 2006 By 5 Comments
… get “SolidDB2″ as result. mysql> update test2 set names=’SolidDB3′ where id=2; ERROR 1213 (40001): Deadlock found when trying to get lock… id=1; ERROR 1213 (40001): Deadlock found when trying to get lock; try restarting transaction Session1: Query OK, 1 row affected (9… id=496201; ERROR 1213 (40001): Deadlock found when trying to get lock; try restarting transaction So we can’t run SysBench benchmark…
Post: InnoDB's gap locks
March 27, 2012 By 15 Comments
… reads and to get a consistent Statement based replication. To accomplish that, row level locking databases also acquire gap locks. What is a… lock is a lock on the gap between index records. Thanks to this gap lock, when you run the same query twice, you get… to get the same value twice. To accomplish that, InnoDB locks all index records found by the WHERE clause with an exclusive lock…
Post: PHP Sessions - Files vs Database Based
March 27, 2007 By 38 Comments
… session you can use GET_LOCK to get same behavior. In the start of the session you can do SELECT GET_LOCK(”,10) and in… release lock – as soon as connection is closed the lock is automatically released. The value 10 in GET_LOCK is timeout in seconds – if lock can’t be granted for this amount of time it will return “0″ indicating lock…
Post: How fast is FLUSH TABLES WITH READ LOCK?
April 24, 2010 By 30 Comments
… in the command. Requesting the lock The FLUSH TABLES WITH READ LOCK command immediately requests the global read lock. As soon as this… for the lock Before the FLUSH TABLES WITH READ LOCK command can successfully acquire the lock, anything else that currently holds the lock must…. It’s waiting to get the lock. Flushing tables After the FLUSH TABLES WITH READ LOCK command finally acquires the lock, it must begin…
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
… see what happens in that case. Metadata Locking and Query Cache How does metadata locking behave with query_cache? That is an… in the table_cache change anything with respect to metadata locks. Metadata Locking and Table Cache No matter if a connection accesses… threads can get piled up waiting for table metadata lock bringing down the MySQL server or causing all the connections to get depleted…
Comment: Watch out for your CRON jobs
October 14, 2009 By 19 Comments
… causing other script to get the same lock. It is much harder to “steal” the lock which is taken by GET_LOCK. On other hand if MySQL server goes away or connection is closed the GET_LOCK lock is gone while lock… is database related GET_LOCK is great because if you lose connection you have aborted the script anyway. Whatever locking method you chose…
Comment: Index lock and adaptive search - next two biggest InnoDB problems
February 19, 2012 By 12 Comments
… == BTR_MODIFY_TREE) { 546 mtr_x_lock(dict_index_get_lock(index), mtr); ==> writer aqcuire execlusive lock 547 548 } else if (latch_mode == BTR…_contains(mtr, dict_index_get_lock(index), 551 MTR_MEMO_X_LOCK)); 552 } else { 553 mtr_s_lock(dict_index_get_lock(index), mtr); ===> all other… Mutex at 0x2d07c648 ‘&trx_doublewrite->mutex’ 2 lock on RW-latch at 0x2d881108 ‘&new_index->lock‘ 212 Mutex at 0x2d0777a8 ‘&log_sys…
