Re: Group-wise Maximum performance

[Felix Geerinckx]

Jon Richards wrote:

> SELECT data
> FROM d s1
> WHERE time=(SELECT MAX(s2.time)
> FROM d s2
> WHERE s1.name = s2.name);
>
> This does work but on a database with >20,000 rows it takes 1 minute to return the values
> (whereas only .06 of a second to return all the values!)

Are your time and name columns indexed? Could you show the result of

describe d;

--
felix