I’m now at MySQL Conference and have just finished my New Subquery Optimizations in MySQL 6.0 talk. If you’re eager to get the slides, here is the link to the pdf file and a mirror.
The talk has the same name as this MySQL University session but the slides have been thoroughly re-worked, and also there is new content:
- More detailed explanation of subquery handling in 4.1/5.x
- More reliable/justified benchmark numbers
- Observations about subquery demographics
- An attempt at comparative analysis of how MySQL’s subquery strategies compare to PostgreSQL’s
- And a slide #28 that explains why we’re looking at PostgreSQL all the time
Have a nice viewing. And, if you get subqueries that should be fast but aren’t, we’re now actively looking at every subquery performance bug we get and will appreciate any input.
Sergei Petrunia's blog 