I was recently debugging a long running database query. In most cases MySQL’s Slow Query Log is a great debugging tool for that. However, in this case I found MySQL’s show processlist to be a better fit. What show processlist … Continue reading
Some time ago we posted about how to install XDebug and KCacheGrind. I think anyone serious about PHP performance should keep those tools handy and in regular use. And it just so happens they helped us uncover a huge performance … Continue reading
A client recently reached out in regard to a reproducible performance problem on their WordPress site. The use case and conditions were as follows: Performance was fine until a change happened to the wp_posts or wp_term_relationships tables (i.e. when a … Continue reading
Here’s another example of why it’s always a good idea to refer to execution plans and test different query options. Here’s a query I was running as part of some manual data work: select ua.* from vn_user_achievements ua where exists … Continue reading
Just after a late night deployment I received this error message while running queries against the production database I just deployed to: Got error 28 from storage engine query I could connect to the database fine, but any database query … Continue reading
A client shot me an email asking for help w/a PlainCart installation he’s trying to setup. The symptom was that the supposed login credentials of admin, admin weren’t working. Reproducing the problem was simple enough, going to the login page … Continue reading
I was recently asked about whether column order matters in composite indexes, and if so, to what extent. I recall this being the case when working with SQL Server 2000 and 2005, so I became curious how MySQL handled scenarios … Continue reading
