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help / color / mirror / Atom feedFrom: 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 23:03:00 +1200
Message-ID: <CAApHDvoQRoKHNfTaw+Sn=bZGKVmn8W-5yBPGP7+98mWJz5A9uQ@mail.gmail.com> (raw)
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On Tue, 27 Aug 2024 at 14:03, Tom Lane <[email protected]> wrote:
> Yeah, I got that same result by bisecting. It seems like it's
> somehow related to the cast to information_schema.sql_identifier:
> we are able to get rid of that normally but seem to fail to do so
> in this query.
In case it saves you a bit of time, I stripped as much of the
unrelated stuff out as I could and got:
create table t (a name, b int);
explain select * from (select a::varchar,b from (select distinct a,b
from t) st) t right join t t2 on t.b=t2.b where t.a='test';
getting rid of the cast or swapping to INNER JOIN rather than RIGHT
JOIN means that qual_is_pushdown_safe() gets a Var rather than a
PlaceHolderVar.
David
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To: [email protected]
Cc: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected]
Subject: Re: Significant Execution Time Difference Between PG13.14 and PG16.4 for Query on information_schema Tables.
In-Reply-To: <CAApHDvoQRoKHNfTaw+Sn=bZGKVmn8W-5yBPGP7+98mWJz5A9uQ@mail.gmail.com>
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