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Re: Index-only scan returns incorrect results when using acomposite GIST index with a gist_trgm_ops column. - Mailing list pgsql-bugs

From Kyotaro HORIGUCHI
Subject Re: Index-only scan returns incorrect results when using acomposite GIST index with a gist_trgm_ops column.
Date
Msg-id 20180118.192009.05328325.horiguchi.kyotaro@lab.ntt.co.jp
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In response to Re: Index-only scan returns incorrect results when using a compositeGIST index with a gist_trgm_ops column.  (Andrey Borodin <x4mmm@yandex-team.ru>)
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At Thu, 18 Jan 2018 12:57:38 +0500, Andrey Borodin <x4mmm@yandex-team.ru> wrote in
<62C2B9A0-51BC-40FF-9BCA-F203784CB9C1@yandex-team.ru>
> Hello!
> > 18 янв. 2018 г., в 10:48, Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp> написал(а):
> >
> > Gist imposes the ninth strategy to perform index only scan but
> > planner is not considering that
> > ....
> > Please find the attached patch.
> I agree with you that current behavior is a bug and your patch seems correct.
> I'm a bit worried about ninth strategy words: fetch is not necessary now, if opclass lacks compress methods - index
onlyscan is possible. See https://github.com/postgres/postgres/commit/d3a4f89d8a3e500bd7c0b7a8a8a5ce1b47859128 for
details.

It is true. I don't think that fetch for trigm is feasible but it
is workable if created.

> Though there are tests in cube and seg for that, if your patch passes check-world, than this behavior is not
affected.

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center

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