Re: DISTINCT -> GROUP BY
От | David Fetter |
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Тема | Re: DISTINCT -> GROUP BY |
Дата | |
Msg-id | 20080603140306.GD22141@fetter.org обсуждение исходный текст |
Ответ на | Re: DISTINCT -> GROUP BY ("Pavel Stehule" <pavel.stehule@gmail.com>) |
Ответы |
Re: DISTINCT -> GROUP BY
Re: DISTINCT -> GROUP BY |
Список | pgsql-hackers |
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 nice to see that this is kinda on the TODO, but it doesn't address the question I asked, which is, "how would I get the planner to rewrite DISTINCTs as the equivalent GROUP BYs?" :) Any hints? Cheers, David. -- David Fetter <david@fetter.org> http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fetter@gmail.com Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate
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