Disqus - Latest Comments for perrinharkins

Re: paperplanes. MySQL No-Nos: ORDER BY RAND()

perrinharkins — Wed, 19 Aug 2009 08:00:44 -0000

The "order by" is not able to use the index on the primary key for sorting in either query, so it sounds like the only thing that's faster here is retrieving the rows for the internal sort.

Re: paperplanes. MySQL No-Nos: ORDER BY RAND()

perrinharkins — Tue, 18 Aug 2009 13:44:11 -0000

This doesn't make sense to me. Why would the second query behave any better? It still has to generate a random number for every row in the table and order by it.