The Layershift Logbook

A query that used to be quick just showed up in your slow query log. Nobody rewrote it. Nobody touched the schema. Yet there it is, slower than it was last month. That single log line is often the first hard evidence that your database is drifting out of alignment with how it's being used. The trick is knowing how to read it, because the log tells you what is slow but leaves you to work out why.