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David Rowley 887a232371 Fix issue with ORDER BY / DISTINCT aggregates and FILTER 
1349d2790 added support so that aggregate functions with an ORDER BY or
DISTINCT clause could make use of presorted inputs to avoid an implicit
sort within nodeAgg.c.  That commit failed to consider that a FILTER
clause may exist that filters rows before the aggregate function
arguments are evaluated.  That can be problematic if an aggregate
argument contains an expression which could error out during evaluation.
It's perfectly valid to want to have a FILTER clause which eliminates
such values, and with the pre-sorted path added in 1349d2790, it was
possible that the planner would produce a plan with a Sort node above
the Aggregate to perform the sort on the aggregate's arguments long before
the Aggregate node would filter out the non-matching values.

Here we fix this by inspecting ORDER BY / DISTINCT aggregate functions
which have a FILTER clause to see if the aggregate's arguments are
anything more complex than a Var or a Const.  Evaluating these isn't
going to cause an error.  If we find any non-Var, non-Const parameters
then the planner will now opt to perform the sort in the Aggregate node
for these aggregates, i.e. disable the presorted aggregate optimization.

An alternative fix would have been to completely disallow the presorted
optimization for Aggrefs with any FILTER clause, but that wasn't done as
that could cause large performance regressions for queries that see
significant gains from 1349d2790 due to presorted results coming in from
an Index Scan.

Backpatch to 16, where 1349d2790 was introduced

Author: David Rowley <dgrowleyml@gmail.com>
Reported-by: Kaimeh <kkaimeh@gmail.com>
Diagnosed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CAK-%2BJz9J%3DQ06-M7cDJoPNeYbz5EZDqkjQbJnmRyQyzkbRGsYkA%40mail.gmail.com
Backpatch-through: 16
2025-04-20 22:12:59 +12:00
config Log LLVM library version in configure output. 2023-10-22 14:23:11 +13:00
contrib Be more wary of corrupt data in pageinspect's heap_page_items(). 2025-04-19 16:37:42 -04:00
doc Doc: remove long-obsolete advice about generated constraint names. 2025-04-10 14:49:22 -04:00
src Fix issue with ORDER BY / DISTINCT aggregates and FILTER 2025-04-20 22:12:59 +12:00
.cirrus.star ci: Prepare to make compute resources for CI configurable 2023-08-23 15:15:28 -07:00
.cirrus.tasks.yml ci: Upgrade FreeBSD image 2025-03-05 10:29:03 -05:00
.cirrus.yml ci: Make compute resources for CI configurable 2023-08-23 15:15:28 -07:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.editorconfig Add .editorconfig 2019-12-18 09:13:13 +01:00
.git-blame-ignore-revs Add b334612b8 to .git-blame-ignore-revs. 2023-06-20 09:52:52 -04:00
.gitattributes Exclude LLVM files from whitespace checks 2024-11-27 11:09:38 +01:00
.gitignore Update top-level .gitignore. 2022-12-04 15:23:00 -05:00
aclocal.m4 autoconf: Move export_dynamic determination to configure 2022-12-06 18:55:28 -08:00
configure Fix detection and handling of strchrnul() for macOS 15.4. 2025-04-01 16:49:51 -04:00
configure.ac Fix detection and handling of strchrnul() for macOS 15.4. 2025-04-01 16:49:51 -04:00
COPYRIGHT Update copyright for 2025 2025-01-01 11:21:54 -05:00
GNUmakefile.in Integrate pg_bsd_indent into our build/test infrastructure. 2023-02-12 12:22:21 -05:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Dynamically find correct installation docs in Makefile. 2022-01-19 14:48:25 +01:00
meson.build Fix detection and handling of strchrnul() for macOS 15.4. 2025-04-01 16:49:51 -04:00
meson_options.txt meson: Attach colon to keyword argument 2023-06-29 12:53:41 +02:00
README Canonicalize some URLs 2020-02-10 20:47:50 +01:00
README.git Canonicalize some URLs 2020-02-10 20:47:50 +01:00

README 

PostgreSQL Database Management System
=====================================

This directory contains the source code distribution of the PostgreSQL
database management system.

PostgreSQL is an advanced object-relational database management system
that supports an extended subset of the SQL standard, including
transactions, foreign keys, subqueries, triggers, user-defined types
and functions.  This distribution also contains C language bindings.

PostgreSQL has many language interfaces, many of which are listed here:

	https://www.postgresql.org/download/

See the file INSTALL for instructions on how to build and install
PostgreSQL.  That file also lists supported operating systems and
hardware platforms and contains information regarding any other
software packages that are required to build or run the PostgreSQL
system.  Copyright and license information can be found in the
file COPYRIGHT.  A comprehensive documentation set is included in this
distribution; it can be read as described in the installation
instructions.

The latest version of this software may be obtained at
https://www.postgresql.org/download/.  For more information look at our
web site located at https://www.postgresql.org/.