…virtual machines tend to handle process scheduling and timing much differently than traditional hardware, and I’ve… example, if you see a large number of long-running queries in the output of SHOW PROCESSLIST…top of a clustered filesystem with an external lock manager. You might say that MySQL/NDB …
Post: MySQL and Percona Server in LinkBench benchmark
May 8, 2013 By 18 Comments
…long, unsigned long, unsigned long, unsigned long, long, unsigned long) … 31.41% 15534570 mysqld mysqld [.] rw_lock_x_lock_func(rw_lock_t*, unsigned long, char const*, unsigned long) | — rw_lock_x_lock… mysqld mysqld [.] ut_delay(unsigned long) So basically most of the time 5.6.11 spent in LRU_…
Post: Is Synchronous Replication right for your app?
May 14, 2013 By 18 Comments
… all sorts modifications floating around as long as they don’t touch the same row. Row locks are held for modifications until… (simultaneously) establish global ordering for the transaction, so by the time the original node gets acknowledgement of the transaction back from… will take the 1 RTT). The other transactions will lock wait until the lock(s) they need are available. The application just…
Post: MySQL 5.6 Compatible Percona Toolkit 2.2 Released
March 25, 2013 By 2 Comments
… tries and wait time between tries for all operations are configurable. Also, we removed –lock-wait-timeout which set innodb_lock_wait_timeout… in 2.2 to make their run-related options (–run-time, –interval, –iterations) standard. If you hadn’t noticed, one tool… forever by default, so specify –iterations or –run-time to limit how long they run. There are more changes in addition to…
Post: Galera Flow Control in Percona XtraDB Cluster for MySQL
May 2, 2013 By 5 Comments
…. A large fc_limit in this case might mean a long wait before flow control gets relaxed again. However, this was… node by simply by running “FLUSH TABLES WITH READ LOCK“, or perhaps by “LOCK TABLE”, in which case flow control will kick… TABLES WITH READ LOCK on node3: [root@node3 ~]# myq_status wsrep Wsrep Cluster Node Queue Ops Bytes Flow Conflct time name P…
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
… metadata locks on the table it has accessed for as long as the transaction is open. Since an open transaction retains metadata locks… finally DROP tmp_table. Let’s see another example, this time trying a RENAME: session2 > RENAME TABLE test to test_2… would be blocked as well at the time when the ALTER is waiting for metadata locks. Let’s see this in action…
Post: How fast is FLUSH TABLES WITH READ LOCK?
April 24, 2010 By 30 Comments
… take an extremely long time on production systems, measured in many minutes, or potentially even hours. And during this time, the server will… READ LOCK command itself will block until the other queries finish and all locks are released. This can take a very long time. It… long time to flush. During that time, the entire system is still locked. After all the data is finished, the FLUSH TABLES WITH READ LOCK…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…stmt_resetblogpercona.commanual Com_stmt_send_long_datablogpercona.commanual Com_truncateblogpercona.commanual …lock_current_waitsblogpercona.commanual Innodb_row_lock_timeblogpercona.commanual Innodb_row_lock_time_avgblogpercona.commanual Innodb_row_lock_time_maxblogpercona.commanual Innodb_row_lock…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
… set a low enough value for long_query_time. We normally use a value of long_query_time=0, because if you set it… the slow query log: # Time: 111229 3:02:26 # User@Host: msandbox[msandbox] @ localhost [] # Query_time: 2.365434 Lock_time: 0.000000 Rows_sent…: 1 Schema: test Last_errno: 0 Killed: 0 # Query_time: 0.117904 Lock_time: 0.002886 Rows_sent: 1 Rows_examined: 655360 Rows…
Post: MySQL Backup tools used by Percona Remote DBA for MySQL
March 13, 2013 By 8 Comments
… into how we could further improve lock times here when non-transactional tables are used Almost no locking, if not using myisam tables… for different types of restores Strategies on retention dailies weeklies, long term backups Decompressing Percona XtraBackup for MySQL in parallel using…
