Random MySQL performance tuning stuff
If you’re using InnoDB, ensure innodb_buffer_pool_size is set to a decent value – I choose about 25% of physical memory… ideally this is larger than your dataset size, but obviously may not be...
View ArticleMySQL update/write query analysis (query profiling)
Do you have a slow MySQL update/insert/delete query? Obviously, for ‘SELECT’ queries you can prepend the query with “EXPLAIN ” – however that doesn’t work for the other query types...
View ArticlePostgreSQL unbuffered queries and PHP (cursors)
From using MySQL, I’ve used the ‘unbuffered queries‘ feature a number of times. It’s where you don’t fetch the entire resultset into memory at once – which is necessary if you’re retrieving more data...
View ArticleMySQL Max_connections stuck on 214 ?
I found MySQL was being annoying earlier and not ‘accepting’ my max_connections = 450 directive on a Debian Wheezy install, and being seemingly stuck on having 214 connections…. It turns out, Debian...
View ArticleCleaning up a lot of WordPress _transients
WordPress seems to like hiding a load of ‘transient’ (cacheable) stuff in it’s wp_options table. Unfortunately for one site, it seems it didn’t bother to clean up the transient stuff, leaving behind...
View Articlefixing/restablishing mysql replication with rsync
One approach to fixing a broken MySQL replication setup…. using rsync. So, with a standard MySQL master/slave (or master/replica if you’re more PC than me) sometimes the replication gets messed up (eg...
View ArticleFinding and killing long running MySQL queries
Sometimes (Woocommerce?) related queries on a MySQL server can seemingly run forever and eventually lead to the server being clogged up (and few free connections). Something like this can help …. (i.e....
View ArticleBash / MySQL queries…
I “woke up” and realised I often do this wrong …. (too many connections/individual queries on MySQL) when the query is returning simple values (single word like things) for each field.As a means of...
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