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

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>

To: nikhil raj <nikhilraj474@gmail.com>

Cc: "pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>, NIKITA PATEL <patelnikita1411@gmail.com>, Patel Khushbu <patelkhushbu2067@gmail.com>

Date: 2024-08-27T01:40:13Z

Lists: pgsql-hackers, pgsql-general

nikhil raj <nikhilraj474@gmail.com> writes:
> I've encountered a noticeable difference in execution time and query
> execution plan row counts between PostgreSQL 13 and PostgreSQL 16 when
> running a query on information_schema tables. Surprisingly, PostgreSQL 16
> is performing slower than PostgreSQL 13.

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.

			regards, tom lane

Commits

Avoid inserting PlaceHolderVars in cases where pre-v16 PG did not.
- b43110869fd8 17.0 landed
- 80d9c07a4a8c 16.5 landed
- cb8e50a4a09f 18.0 landed
Remove one memoize test case added by commit 069d0ff02.
- 3409b4db631f 18.0 landed