From 24987c6f0687576da97b593c6dd5740ccdd23277 Mon Sep 17 00:00:00 2001 From: Bruce Momjian Date: Sat, 3 May 2025 12:57:18 -0400 Subject: [PATCH] doc PG 18 relnotes: add GROUP BY column elimination item With a nod to PG 9.6. Reported-by: jian he Discussion: https://postgr.es/m/CACJufxEqs=EXZETwtaOooTFhZrtxvSWg8M2uPfzjNtS3wQ6Dzw@mail.gmail.com --- doc/src/sgml/release-18.sgml | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/doc/src/sgml/release-18.sgml b/doc/src/sgml/release-18.sgml index 66cdeb67961..33e9199d758 100644 --- a/doc/src/sgml/release-18.sgml +++ b/doc/src/sgml/release-18.sgml @@ -284,6 +284,23 @@ This optimization can be disabled using enable_distinct_reordering. + + + + +Ignore GROUP BY columns that are functionally dependent on other columns (Zhang Mingli, Jian He, David Rowley) +§ + + + +If a GROUP BY clause includes all columns of a unique index, as well as other columns of the same table, those other columns are redundant and can be dropped +from the grouping. This was already true for non-deferred primary keys. + + +