Re: BUG #18477: A specific SQL query with "ORDER BY ... NULLS FIRST" is performing poorly if an ordering column is n

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От David Rowley
Тема Re: BUG #18477: A specific SQL query with "ORDER BY ... NULLS FIRST" is performing poorly if an ordering column is n
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Msg-id CAApHDvoQmbesAm93i6mC_kzi_6x3ng-XT2Na9OFfSnw=eGisag@mail.gmail.com
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Ответ на Re: BUG #18477: A specific SQL query with "ORDER BY ... NULLS FIRST" is performing poorly if an ordering column is n  (Laurenz Albe <laurenz.albe@cybertec.at>)
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On Thu, 6 Jun 2024 at 20:10, Laurenz Albe <laurenz.albe@cybertec.at> wrote:
>
> On Thu, 2024-06-06 at 17:04 +1200, David Rowley wrote:
> > If the user has some genuine reason for creating a NULLS FIRST index
> > for some other query, then it might be nice if we were able to use
> > that index for Merge Joins instead of them having to create another
> > index to speed up the join query.
>
> I cannot imagine a genuine reason for creating a NULLS FIRST index
> on a NOT NULL column, but perhaps I am too narrow-minded.

You didn't quote the part where I said "if you had two nullable
columns". It might be worth rereading what I wrote and taking the time
to understand it.

David



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