… set innodb_lock_wait_timeout because that now conflicts, or is at least confused with, lock_wait_timeout (introduced in MySQL 5.5) for metadata locks. Now –set-vars is used to set both of these (or any) system variables. For…
Post: Is Synchronous Replication right for your app?
May 14, 2013 By 18 Comments
…groups, but also updates groups with some metadata: BEGIN; INSERT INTO users_groups (user_id,…other transactions will lock wait until the lock(s) they need are available. The application just waits in those…typical answers. However, this means more latency waiting for a write to go through, and …
Post: Percona Server for MySQL 5.5.30-30.2 now available
April 10, 2013 By 10 Comments
… milestone at Launchpad. New Features: Percona Server for MySQL has implemented priority connection scheduling for the Thread Pool. (Alexey Kopytov) Percona Server… for the upstream bug #63144. CREATE TABLE or CREATE TABLE IF NOT EXISTS statements on an existing table could wait on a metadata lock… (Hrvoje Matijakovic), bug fixed #1154954 (Hrvoje Matijakovic). Release notes for Percona Server for MySQL 5.5.30-30.2 are available in…
Comment: Implications of Metadata Locking Changes in MySQL 5.5
March 27, 2013 By 9 Comments
… would hold any row lock. The point was to show the implications of a transaction not holding metadata locks on tables that have… scenario in that you have row locks blocking the ALTER, while the post deals with metadata locks. If you can enable the InnoDB… transaction; select * from t1 where id=3 for update; — session 2 set innodb_lock_wait_timeout=1; alter table t1 engine=innodb; And…
Post: Percona Server 5.5.30-30.2 rerelease fixes non-restart issue
April 24, 2013 By Leave a Comment
….30-30.2 — New Features: Percona Server for MySQL has implemented priority connection scheduling for the Thread Pool. (Alexey Kopytov) Percona Server… for the upstream bug #63144. CREATE TABLE or CREATE TABLE IF NOT EXISTS statements on an existing table could wait on a metadata lock… (Hrvoje Matijakovic), bug fixed #1154954 (Hrvoje Matijakovic). Release notes for Percona Server for MySQL 5.5.30-30.2 are available in…
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
… waiting for metadata locks. Let’s see the profiling information for this query: session10 > show profile for query 11; +——————————–+———-+ | Status | Duration | +——————————–+———-+ | starting | 0.000018 | | Waiting for query cache lock…
Comment: Implications of Metadata Locking Changes in MySQL 5.5
February 2, 2013 By 9 Comments
Marc, Yes when queries are waiting for metadata locks, the thread state is “Waiting for table metadata lock” in the processlist. Probably we can have a new feature in Percona Server to tackle the issue that you face during DDLs.
Post: MySQL 5.5 lock_wait_timeout: patience is a virtue, and a locked server
February 28, 2013 By 5 Comments
… the MySQL 5.5 docs for lock_wait_timeout: This variable specifies the timeout in seconds for attempts to acquire metadata locks. The permissible values range… variable specifies the timeout in seconds for attempts to acquire metadata locks,” then why isn’t it called metadata_lock_wait_timeout? In conclusion: be careful…
Comment: MySQL optimizer: ANALYZE TABLE and Waiting for table flush
February 28, 2013 By 3 Comments
@Vojtech no, the same locks are used in MySQL 5.6 @ymhctt I think they are different things. Metadata lock is used to avoid DDL while a transaction is active and modifying a table. For metadata lock you would see “Waiting for table metadata lock“.
Comment: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
The above scenario is when you would see the “Waiting for table metadata lock” status, right? I’ve encountered this issue about every time… script that will kill all sleeping threads over 1 second for the database i’m working on. If not the DDL…
