From: Tatsuo Ishii <ishii@postgresql.org>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Add IGNORE NULLS/RESPECT NULLS option to Window functions.
Date: Fri, 03 Oct 2025 00:59:45 +0000
Message-ID: <E1v4U9B-001BCJ-00@gemulon.postgresql.org> (raw)
Add IGNORE NULLS/RESPECT NULLS option to Window functions.
Add IGNORE NULLS/RESPECT NULLS option (null treatment clause) to lead,
lag, first_value, last_value and nth_value window functions. If
unspecified, the default is RESPECT NULLS which includes NULL values
in any result calculation. IGNORE NULLS ignores NULL values.
Built-in window functions are modified to call new API
WinCheckAndInitializeNullTreatment() to indicate whether they accept
IGNORE NULLS/RESPECT NULLS option or not (the API can be called by
user defined window functions as well). If WinGetFuncArgInPartition's
allowNullTreatment argument is true and IGNORE NULLS option is given,
WinGetFuncArgInPartition() or WinGetFuncArgInFrame() will return
evaluated function's argument expression on specified non NULL row (if
it exists) in the partition or the frame.
When IGNORE NULLS option is given, window functions need to visit and
evaluate same rows over and over again to look for non null rows. To
mitigate the issue, 2-bit not null information array is created while
executing window functions to remember whether the row has been
already evaluated to NULL or NOT NULL. If already evaluated, we could
skip the evaluation work, thus we could get better performance.
Author: Oliver Ford <ojford@gmail.com>
Co-authored-by: Tatsuo Ishii <ishii@postgresql.org>
Reviewed-by: Krasiyan Andreev <krasiyan@gmail.com>
Reviewed-by: Andrew Gierth <andrew@tao11.riddles.org.uk>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: David Fetter <david@fetter.org>
Reviewed-by: Vik Fearing <vik@postgresfriends.org>
Reviewed-by: "David G. Johnston" <david.g.johnston@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Discussion: https://postgr.es/m/flat/CAGMVOdsbtRwE_4+v8zjH1d9xfovDeQAGLkP_B6k69_VoFEgX-A@mail.gmail.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/25a30bbd4235a49c854036c84fe90f2bc5a87652
Modified Files
--------------
doc/src/sgml/func/func-window.sgml | 38 +--
doc/src/sgml/syntax.sgml | 10 +-
src/backend/catalog/sql_features.txt | 2 +-
src/backend/executor/nodeWindowAgg.c | 467 ++++++++++++++++++++++++++++++++---
src/backend/optimizer/util/clauses.c | 1 +
src/backend/parser/gram.y | 19 +-
src/backend/parser/parse_func.c | 9 +
src/backend/utils/adt/ruleutils.c | 7 +-
src/backend/utils/adt/windowfuncs.c | 10 +
src/include/nodes/parsenodes.h | 1 +
src/include/nodes/primnodes.h | 13 +
src/include/parser/kwlist.h | 2 +
src/include/windowapi.h | 6 +
src/test/regress/expected/window.out | 406 ++++++++++++++++++++++++++++++
src/test/regress/sql/window.sql | 162 ++++++++++++
15 files changed, 1092 insertions(+), 61 deletions(-)
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-committers@postgresql.org
Cc: ishii@postgresql.org, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Add IGNORE NULLS/RESPECT NULLS option to Window functions.
In-Reply-To: <E1v4U9B-001BCJ-00@gemulon.postgresql.org>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox