Re: [HACKERS] DISTINCT - GROUP BY

2008-06-04 Thread Decibel!
On Jun 3, 2008, at 9:03 AM, David Fetter wrote: On Tue, Jun 03, 2008 at 03:36:44PM +0200, Pavel Stehule wrote: Hello David http://www.postgresql.org/docs/faqs.TODO.html Consider using hash buckets to do DISTINCT, rather than sorting This would be beneficial when there are few distinct values.

[HACKERS] DISTINCT - GROUP BY

2008-06-03 Thread David Fetter
Folks, I've noticed that queries of the form SELECT DISTNCT foo, bar, baz FROM quux WHERE ... perform significantly worse than the equivalent using GROUP BY. SELECT foo, bar, baz FROM quux WHERE ... GROUP BY foo, bar, baz Where would I start looking in order to make them actually equivalent

Re: [HACKERS] DISTINCT - GROUP BY

2008-06-03 Thread Pavel Stehule
Hello David http://www.postgresql.org/docs/faqs.TODO.html Consider using hash buckets to do DISTINCT, rather than sorting This would be beneficial when there are few distinct values. This is already used by GROUP BY. Regards Pavel Stehule 2008/6/3 David Fetter [EMAIL PROTECTED]: Folks, I've

Re: [HACKERS] DISTINCT - GROUP BY

2008-06-03 Thread David Fetter
On Tue, Jun 03, 2008 at 03:36:44PM +0200, Pavel Stehule wrote: Hello David http://www.postgresql.org/docs/faqs.TODO.html Consider using hash buckets to do DISTINCT, rather than sorting This would be beneficial when there are few distinct values. This is already used by GROUP BY. It's

Re: [HACKERS] DISTINCT - GROUP BY

2008-06-03 Thread Pavel Stehule
2008/6/3 David Fetter [EMAIL PROTECTED]: On Tue, Jun 03, 2008 at 03:36:44PM +0200, Pavel Stehule wrote: Hello David http://www.postgresql.org/docs/faqs.TODO.html Consider using hash buckets to do DISTINCT, rather than sorting This would be beneficial when there are few distinct values. This