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From: David Rowley <[email protected]>
To: Tom Lane <[email protected]>
Cc: nikhil raj <[email protected]>
Cc: pgsql-generallists.postgresql.org <[email protected]>
Cc: NIKITA PATEL <[email protected]>
Cc: Patel Khushbu <[email protected]>
Subject: Re: Significant Execution Time Difference Between PG13.14 and PG16.4 for Query on information_schema Tables.
Date: Tue, 27 Aug 2024 13:50:56 +1200
Message-ID: <CAApHDvpRxyw1G2HVkA=PM5Uqh59moOFqPXyMTsEDUadKo2fQTA@mail.gmail.com> (raw)
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On Tue, 27 Aug 2024 at 13:40, Tom Lane <[email protected]> wrote:
> Yeah, it looks like that condition on "table_name" is not getting
> pushed down to the scan level anymore.  I'm not sure why not,
> but will look closer tomorrow.

I was looking for the offending commit as at first I thought it might
be related to Memoize. It does not seem to be.

I get the following up until 2489d76c, and from then on, it's a subquery filter.

 ->  Index Scan using pg_class_relname_nsp_index on pg_class r_2
(cost=0.27..8.30 rows=1 width=8) (actual time=0.004..0.004 rows=0
loops=1)
        Index Cond: (relname = 't_c56ng1_repository'::name)
        Filter: ((relkind = ANY ('{r,p}'::"char"[])) AND
pg_has_role(relowner, 'USAGE'::text))

So looks like it was the "Make Vars be outer-join-aware." commit that
changed this.

David

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  Subject: Re: Significant Execution Time Difference Between PG13.14 and PG16.4 for Query on information_schema Tables.
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