From: Tom Lane <tgl@sss.pgh.pa.us>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Fix unnecessary use of moving-aggregate mode with non-moving fra
Date: Wed, 27 Mar 2024 17:39:52 +0000
Message-ID: <E1rpXFg-005xTB-AR@gemulon.postgresql.org> (raw)
Fix unnecessary use of moving-aggregate mode with non-moving frame.
When a plain aggregate is used as a window function, and the window
frame start is specified as UNBOUNDED PRECEDING, the frame's head
cannot move so we do not need to use moving-aggregate mode. The check
for that was put into initialize_peragg(), failing to notice that
ExecInitWindowAgg() calls that function before it's filled in
winstate->frameOptions. Since makeNode() would have zeroed the field,
this didn't provoke uninitialized-value complaints, nor would the
erroneous decision have resulted in more than a little inefficiency.
Still, it's wrong, so move the initialization of
winstate->frameOptions earlier to make it work properly.
While here, also fix a thinko in a comment. Both errors crept in in
commit a9d9acbf2 which introduced the moving-aggregate mode.
Spotted by Vallimaharajan G. Back-patch to all supported branches.
Discussion: https://postgr.es/m/18e7f2a5167.fe36253866818.977923893562469143@zohocorp.com
Branch
------
REL_16_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/a94f51a7bfc9e65ce3799d8cb12945bd596c5ba8
Modified Files
--------------
src/backend/executor/nodeWindowAgg.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: tgl@sss.pgh.pa.us, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Fix unnecessary use of moving-aggregate mode with non-moving fra
In-Reply-To: <E1rpXFg-005xTB-AR@gemulon.postgresql.org>
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