From: Tom Lane <tgl@sss.pgh.pa.us>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Remove one memoize test case added by commit 069d0ff02.
Date: Fri, 30 Aug 2024 16:42:23 +0000
Message-ID: <E1sk4hb-0029Eo-3Z@gemulon.postgresql.org> (raw)
Remove one memoize test case added by commit 069d0ff02.
This test case turns out to depend on the assumption that a non-Var
subquery output that's underneath an outer join will always get
wrapped in a PlaceHolderVar. But that behavior causes performance
regressions in some cases compared to what happened before v16.
The next commit will avoid inserting a PHV in the same cases where
pre-v16 did, and that causes get_memoized_path to not detect that
a memoize plan could be used.
Commit this separately, in hopes that we can restore the test after
making get_memoized_path smarter. (It's failing to find memoize
plans in adjacent cases where no PHV was ever inserted, so there
is definitely room for improvement there.)
Discussion: https://postgr.es/m/CAG1ps1xvnTZceKK24OUfMKLPvDP2vjT-d+F2AOCWbw_v3KeEgg@mail.gmail.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/3409b4db631f5471696127494e57193350b87b41
Modified Files
--------------
src/test/regress/expected/memoize.out | 30 ------------------------------
src/test/regress/sql/memoize.sql | 11 -----------
2 files changed, 41 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: tgl@sss.pgh.pa.us, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Remove one memoize test case added by commit 069d0ff02.
In-Reply-To: <E1sk4hb-0029Eo-3Z@gemulon.postgresql.org>
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