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Re: sequential scan on select distinct - Mailing list pgsql-performance

From Tom Lane
Subject Re: sequential scan on select distinct
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Msg-id [email protected]
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In response to Re: sequential scan on select distinct  (Greg Stark <[email protected]>)
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Re: sequential scan on select distinct
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Greg Stark <[email protected]> writes:
> why isn't a "skip index scan" plan available? Well, nobody's written the code
> yet.

I don't really think it would be a useful plan anyway.  What *would* be
useful is to support HashAggregate as an implementation alternative for
DISTINCT --- currently I believe we only consider that for GROUP BY.
The DISTINCT planning code is fairly old and crufty and hasn't been
redesigned lately.

            regards, tom lane

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