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Re: GROUP BY vs DISTINCT - Mailing list pgsql-performance

From Tom Lane
Subject Re: GROUP BY vs DISTINCT
Date
Msg-id 22279.1166628998@sss.pgh.pa.us
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In response to Re: GROUP BY vs DISTINCT  ("Peter Childs" <peterachilds@gmail.com>)
List pgsql-performance
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"Peter Childs" <peterachilds@gmail.com> writes:
> Is it actually in the sql spec to sort in a distinct

No.  PG's code that supports GROUP BY is newer and smarter than the code
that supports DISTINCT, is all.  One of the things on the to-do list is
to revise DISTINCT so it can also consider hash-based implementations.
The hard part of that is not to break DISTINCT ON ...

            regards, tom lane

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