… just a moderate load on the host system, DRBD can end up in a split-brain situation. Typically DRBD is run… output of SHOW PROCESSLIST that might be a sign that trouble is brewing. Or if you watch your MySQL server’s memory… in a MySQL Cluster installation are going to be talking to the same set of data nodes on the back end, but…
Post: High-load problems? Investigate them with 'pt-query-digest'
April 23, 2013 By 2 Comments
… appear in processlist. In this case, I extracted the first snapshot from each *-processlist capture (under …, by merging it with another query that ended up having a much better execution plan,…you regularly work with MySQL databases, getting familiar with Percona Toolkit for MySQL will let you do …
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
…MySQL 5.5.3 a statement that opened a table only held meta data locks till the end…| localhost | test | Query | 0 | NULL | show processlist | +—-+———-+———–+——+———+——+———————————+————————————————————-+ 3 rows in…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
I am constantly referring to the amazing MySQL manual, especially the option and variable reference table. But just …
Post: How FLUSH TABLES WITH READ LOCK works with Innodb Tables
March 23, 2012 By 20 Comments
…end causes “field list” operation to be blocked too, which among other tools used by mysql…mysql> show processlist; +——-+——+———–+———-+————+——+——————————+——————————+———–+—————+———–+ | Id | User | Host | db…
Post: MySQL for Hosting Providers - how do they manage ?
November 28, 2008 By 15 Comments
… for future MySQL versions. May be Drizzle will give it a thought ? This surely would help adoption by (especially low end) Hosting… (included in Percona releases) or Log analyzes as well as PROCESSLIST monitoring. This allows you to crack down on users which… very light queries which would not show up in the PROCESSLIST or will not take too much combined time in the…
Post: MySQL 4 to MySQL 5 Upgrade performance regressions
June 6, 2007 By 8 Comments
… am extremely unhappy how MySQL handled this problem. While working for MySQL we spotted this problem early in MySQL 5.0 release cycle… would see queries in “SHOW PROCESSLIST” stuck in “end” stage or have “commit” queries in the processlist for multiple statement transactions. Looking at… should stay on MySQL 4.1 until MySQL has taken it away from you as already happened with MySQL 4.0. MySQL 5.0…
Post: Return of the Query Cache, win a Percona Live ticket
August 26, 2011 By 4 Comments
… query cache and the interface between it and MySQL. It’s now possible to completely disable it, …, that changes the thread’s status in SHOW PROCESSLIST to “Waiting on query cache mutex” when the …is more intuitive for non-programmers anyway. Regardless, the end effect is the same thing: just as you …
Post: MySQL caching methods and tips
April 4, 2011 By 5 Comments
…in order to achieve the desired result. Your end users also care about response times because …methods for MySQL. Popular cache methods The MySQL query cache When the query cache is enabled, MySQL examines … Percona Server even has a state in the processlist ‘waiting on query cache mutex’ so that this…
Post: Percona Toolkit by example - pt-stalk
January 3, 2013 By 3 Comments
… have pt-stalk running 24/7, because problems such as MySQL lockups or spikes of activity typically leave no evidence to… variable from the “show processlist” command, in this case, I’m using the “Host” variable. $ pt-stalk –function processlist –variable Host\ –match…_plugin() { mysqladmin $EXT_ARGV processlist | awk -F\| ‘BEGIN{counter=0} { if ($4 ~ /localhost/ && $7 > 5000 ) counter++ ; } END {print counter}’ } The pt-stalk…
