… status variables that you might want to keep an eye on to prevent a problem before it occurs. For…PRM simply attempt to connect and run a simple query, but it’s always possible to build something …on top of a clustered filesystem with an external lock manager. You might say that MySQL/NDB Cluster …
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
… the profiling information for this query: session10 > show profile for query 11; +——————————–+———-+ | Status | Duration | +——————————–+———-+ | starting | 0.000018 | | Waiting for query cache lock | 0.000003 | | checking query cache for query | 0…
Post: Write contentions on the query cache
September 5, 2012 By 5 Comments
… me that I executed the SHOW PROFILE and SHOW STATUS LIKE ‘Handler%’ with the SQL_NO_CACHE hint. Will …for query cache lock | 0.000004 | | Waiting on query cache mutex | 0.000002 | | Sending data | 0.003407 | | Waiting for query cache lock | 0.000003 | | Waiting on query …
Post: Return of the Query Cache, win a Percona Live ticket
August 26, 2011 By 4 Comments
… theirs changed the wording to “Waiting on query cache lock” instead. This is more intuitive for non-programmers anyway. Regardless, the end effect… in Locked status, now you get a screen full of query cache locks. It makes it impossible to miss serious contention when it happens. For…
Post: Shard-Query EC2 images available
May 11, 2011 By 2 Comments
… run_query script will run one more more semicolon terminated SQL statements. The queries for the benchmark are in ~ec2-user/shard-query/queries.sql… innodb-stats-sample-pages=256 innodb-stats-update-need-lock=0 innodb-status-file innodb-strict-mode innodb-thread-concurrency=0 innodb…
Post: MySQL Query Cache
July 27, 2006 By 70 Comments
…query, have extra space or use different case – these would be different queries for query cache. Only SELECT queries…Query Cache Query Cache Status Query Cache Configuration I would just mention couple of points – as protection from one query wiping your all query cache option query…
Post: Concurrent inserts on MyISAM and the binary log
May 14, 2008 By 7 Comments
… were blocking and the process list was filling up with queries in Locked status. My first thought was that the customer had deleted… and is correct behavior. The statements have to be serialized for the binary log; otherwise replaying the binary log can result… inserts for CREATE … SELECT or INSERT … SELECT statements. If you use mysqladmin debug, you’ll see an ordinary SELECT gets a lock…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
… value for the mutex object (locked=1/free=0) , “waiters flag” is current number of waiters, plus you can see wait status information…, query id 100626 localhost root Updating update iz set pad=’a’ where i=2 *** (1) WAITING FOR THIS LOCK TO BE GRANTED: RECORD LOCKS… SHOW PROCESSLIST showed in SHOW INNODB STATUS, such as statement which is being executed, query id, query status etc. Next section you will see…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…lock_wait_timeoutblogpercona.commanual innodb_locks_unsafe_for…innodb_status_…query_cache_limitblogpercona.commanual query_cache_min_res_unitblogpercona.commanual query_cache_sizeblogpercona.commanual query_cache_typeblogpercona.commanual query_cache_wlock_invalidateblogpercona.commanual query…
Post: Innodb Table Locks
July 31, 2012 By 4 Comments
…LOCK TABLE sbtest WRITE and repeat our update query. We will still see table reported as locked in “IX” in SHOW ENGINE INNODB STATUS… locked explicitly Innodb “converts” table lock to “no lock” hence eliminating conflicts on MySQL level table locks for most queries. Summary: MySQL Table level locks …
