When you DROP or TRUNCATE a table or partition in MySQL and you have a large buffer pool, you may noticed a complete server lock-up or stall of multiple seconds. Mitigation and Workarounds.
Data types matching between the table columns and queries is important – mismatch usually prevents the use of indexes.
Most DBAs know that sub-selects are typically bad for performance, but this example we encountered in the wild illustrates very well just how bad for performance sub-selects can be.
In this article we discuss a list of best practices to help you write queries that perform well and avoid writing queries that end up being unoptimizable.
ORs in SQL queries are bad for performance. Here we describe a technique for doing away with the ORs to improve performance while still retaining functional equivalence of the query.
PMM fix for missing disk stats/metrics on newer kernels.
