Fun MySQL fact of the day: subqueries in MySQL5.5

The year 2013 can be remembered by 3 separate things: Justin Timberlake, the series finale of Breaking Bad, and the release of MySQL 5.6. Though, if you aren't a MySQL historian, the release of MySQL 5.6 may have passed you by and you may have missed the significance as it pertains to subquery optimisation. So, today, we're going to take a quick look back at MySQL 5.5's subquery execution strategy.

Generally speaking, MySQL 5.5's subquery execution strategy can be defined as "simple", and while it's not quite as simple as I'm letting on, we can pretty much lump it into 2 separate strategies:

Sure, there's some more finesse to this and a dependent subquery isn't always the worst choice, but tomorrow, we'll start looking at how MySQL 5.6 solved this limitation. And then we'll never look back.