News for hackers. Stuff that matters.

A comment on On “order by” optimization. Parent comment

Re:On “order by” optimization by midom on Saturday August 01, 2015 @11:15PM (#9989601)
LIMIT 2 is also exposed to this issue, at different data ratios (in my tests up to LIMIT 142, I went through the math).
[ Parent | on HN ]
Re:On “order by” optimization by acqq on Sunday August 02, 2015 @06:37PM (#9992767)
Can you please explain: Does MySQL use index over (b,c) or not where evaluating "where b=X" or not? As I've said, I'd expect any engine which has an index to use it.
[ Parent | on HN ]