Just recently I came across the presentation “Bend SQL to your will with EXPLAIN” by Ligaya Turmelle via the Linked In – MySQL Speakers and Presenters group. Slides available at Slideshare. While I know a little about MySQL, I always enjoy spending time reviewing content when possible, perhaps as a good reference when asked, perhaps to glean some small point of knowledge I didn’t know, or didn’t understand completely, or had forgotten about. It’s also fun to randomly find worthwhile information.
EXPLAIN is an essential tool for MySQL developers, if you don’t know what QEP is, the listed google search link gives you a clear and obvious easy definition (using basic contextual searching techniques). You would then use EXPLAIN to determine the QEP, and then learn how to use it well.
For those that want to learn about EXPLAIN as an essential tool for MySQL developers I recommend you check the presentation out.