| From: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> |
|---|---|
| To: | David Rowley <dgrowleyml(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Kirk Wolak <wolakk(at)gmail(dot)com>, pgsql-general <pgsql-general(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: A performance issue in ROW_NUMBER() OVER(ORDER BY NULL) [27 times slow than OVER()] V14.5 |
| Date: | 2023-02-20 04:54:01 |
| Message-ID: | CAFj8pRAyyMLKDxOp=_0ZOD9P-adeVhZENM9-fBrh8XQX-QWk8A@mail.gmail.com |
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| Lists: | pgsql-general |
po 20. 2. 2023 v 0:26 odesílatel David Rowley <dgrowleyml(at)gmail(dot)com> napsal:
> On Mon, 20 Feb 2023 at 10:18, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > I don't see it at all. Comparing your two test queries on released
> > branches, I see maybe 2x penalty for the ORDER BY NULL, not 30x.
> > (In HEAD there's only about 13% penalty.) I wonder what PG version
> > you are testing.
>
> I suspect ed1a88dda would be what made this faster in master. We'll
> check for peer rows to check "NULL IS NOT DISTINCT FROM NULL" prior to
> that change with the ORDER BY NULL query.
>
yes, I tested it on master, and the query is little bit slower still, but
not too much (27 sec x 24 sec)
Regards
Pavel
>
> David
>
>
>
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