pgsql: Flush Memoize cache when non-key parameters change, take 2

From: David Rowley <drowley(at)postgresql(dot)org>
To: pgsql-committers(at)lists(dot)postgresql(dot)org
Subject: pgsql: Flush Memoize cache when non-key parameters change, take 2
Date: 2021-11-24 10:30:27
Message-ID: E1mppXn-0005UB-Q2@gemulon.postgresql.org
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Flush Memoize cache when non-key parameters change, take 2

It's possible that a subplan below a Memoize node contains a parameter
from above the Memoize node. If this parameter changes then cache entries
may become out-dated due to the new parameter value.

Previously Memoize was mistakenly not aware of this. We fix this here by
flushing the cache whenever a parameter that's not part of the cache
key changes.

Bug: #17213
Reported by: Elvis Pranskevichus
Author: David Rowley
Discussion: https://postgr.es/m/17213-988ed34b225a2862@postgresql.org
Backpatch-through: 14, where Memoize was added

Branch
------
REL_14_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/c2dc7b9e15039ce90c0a631ff291feb81d2c8051

Modified Files
--------------
src/backend/executor/nodeMemoize.c | 38 ++++++++++++++++++++++++++++++++
src/backend/nodes/bitmapset.c | 2 ++
src/backend/nodes/copyfuncs.c | 1 +
src/backend/nodes/outfuncs.c | 1 +
src/backend/nodes/readfuncs.c | 1 +
src/backend/optimizer/plan/createplan.c | 10 ++++++---
src/backend/optimizer/util/clauses.c | 31 ++++++++++++++++++++++++++
src/include/nodes/execnodes.h | 2 ++
src/include/nodes/plannodes.h | 1 +
src/include/optimizer/clauses.h | 2 ++
src/test/regress/expected/memoize.out | 39 +++++++++++++++++++++++++++++++++
src/test/regress/sql/memoize.sql | 20 +++++++++++++++++
12 files changed, 145 insertions(+), 3 deletions(-)

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