public inbox for [email protected]
help / color / mirror / Atom feedFrom: Tom Lane <[email protected]>
To: David Rowley <[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: Mon, 26 Aug 2024 22:03:47 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAApHDvpRxyw1G2HVkA=PM5Uqh59moOFqPXyMTsEDUadKo2fQTA@mail.gmail.com>
References: <CALNXOfqDr5jVRZHThyXyNftDuezjxOJB1mqw=4x1T8YBibi6uw@mail.gmail.com>
<CAG1ps1w61XD1LxUf3EBCZ=VR3S_orRj_dk6cxmO5KusBVyrgMg@mail.gmail.com>
<CAAvG1pChk3W9MWkK-_JPyUdThSoJhv4MueH5i8cZS2T_HUP5dA@mail.gmail.com>
<CAG1ps1xvnTZceKK24OUfMKLPvDP2vjT-d+F2AOCWbw_v3KeEgg@mail.gmail.com>
<[email protected]>
<CAApHDvpRxyw1G2HVkA=PM5Uqh59moOFqPXyMTsEDUadKo2fQTA@mail.gmail.com>
David Rowley <[email protected]> writes:
> 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.
> So looks like it was the "Make Vars be outer-join-aware." commit that
> changed this.
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.
There was a smaller increase in the runtime at dfb75e478 "Add primary
keys and unique constraints to system catalogs", but that seems to
just be due to there being more rows in the relevant catalogs.
(That's from testing the query in an empty database; probably the
effect of dfb75e478 would be swamped in a production DB anyway.)
regards, tom lane
view thread (22+ messages) latest in thread
reply
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
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: <[email protected]>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox