From: Melanie Plageman <melanieplageman@gmail.com>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Make it cheap to check if a relation is modified by a query
Date: Mon, 30 Mar 2026 13:38:37 +0000
Message-ID: <E1w7CpB-0029eQ-09@gemulon.postgresql.org> (raw)
Make it cheap to check if a relation is modified by a query
Save the range table indexes of result relations and row mark relations
in separate bitmapsets in the PlannedStmt. Precomputing them allows
cheap membership checks during execution. Together, these two groups
approximate all relations that will be modified by a query. This
includes relations targeted by INSERT, UPDATE, DELETE, and MERGE as well
as relations with any row mark (like SELECT FOR UPDATE).
Future work will use information on whether or not a relation is
modified by a query in a heuristic.
PlannedStmt->resultRelations is only used in a membership check, so it
will be removed in a separate commit.
Author: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: David Rowley <dgrowleyml@gmail.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://postgr.es/m/F5CDD1B5-628C-44A1-9F85-3958C626F6A9%40gmail.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/0f4c170cf3b85ef8b092990a88e5b7b50892f7d5
Modified Files
--------------
src/backend/executor/execParallel.c | 7 +++++++
src/backend/optimizer/plan/planner.c | 15 ++++++++++++++-
src/include/nodes/plannodes.h | 6 ++++++
3 files changed, 27 insertions(+), 1 deletion(-)
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To: pgsql-committers@postgresql.org
Cc: melanieplageman@gmail.com, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Make it cheap to check if a relation is modified by a query
In-Reply-To: <E1w7CpB-0029eQ-09@gemulon.postgresql.org>
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