The more I go through others SQL, there are some common mistakes that I see developers making over and over again, so I thought why not start a series of tips that can help developers optimize their queries and avoid common pitfalls. So this post is a part of that series of tips, and this is the first tip "Avoid using a wild card character at the start of a LIKE pattern".
We’ve been getting lots of questions about how MySQL 5.1 optimises queries on partitioned tables. Recently, we added some new information about this to our Internals Manual provided by one of our developers, Sergey Petrunia. (I hope that my edits and formatting haven’t messed up anything — if there are any problems with what’s been published in the Internals Manual, then the fault’s probably mine and not his.)
The new section can be accessed here, and includes coverage of the following topics:
- An overview of how MySQL performs partition pruning
- What partitioning and subpartitioning intervals are, and why they’re important
ONclauses into intervals
- Partition selection
- Where to find partition pruning and selection code in …