Re: How slow is distinct - 2nd - Mailing list pgsql-sql

From Tom Lane
Subject Re: How slow is distinct - 2nd
Date
Msg-id 20689.1033742688@sss.pgh.pa.us
Whole thread Raw
In response to How slow is distinct - 2nd  ("Michael Contzen" <Michael.Contzen@dohle.com>)
List pgsql-sql
"Michael Contzen" <Michael.Contzen@dohle.com> writes:
> [ select distinct takes a long time on 7+ million rows ]

What do you have sort_mem set to?  The default value is mighty small,
and that would translate directly to poor performance in DISTINCT.

Still though, the speed differential against Oracle is surprising,
given that they don't seem to be using a fundamentally different
implementation.  Time to get out the profiler ...
        regards, tom lane


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