Re: GROUP BY vs DISTINCT

On Tue, Dec 19, 2006 at 11:19:39PM -0800, Brian Herlihy wrote:
> Actually, I think I answered my own question already.  But I want to
> confirm - Is the GROUP BY faster because it doesn't have to sort results,
> whereas DISTINCT must produce sorted results?  This wasn't clear to me from
> the documentation.  If it's true, then I could save considerable time by
> using GROUP BY where I have been using DISTINCT in the past.  Usually I
> simply want a count of the distinct values, and there is no need to sort
> for that.

You are right; at the moment, GROUP BY is more intelligent than DISTINCT,
even if they have to compare the same columns. This is, as always, something
that could be improved in a future release, TTBOMK.

/* Steinar */
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