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David Rowley 928df067d1 Fix incorrect targetlist in dummy UNIONs
The prior code, added in 03d40e4b5 attempted to use the targetlist of the
first UNION child when all UNION children were proven as dummy rels.
That's not going to work when some operation atop of the Result node must
find target entries within the Result's targetlist.  This could have been
something as simple as trying to sort the results of the UNION operation,
which would lead to:

ERROR:  could not find pathkey item to sort

Instead, use the top-level UNION's targetlist and fix the varnos in
setrefs.c.  Because set operation targetlists always use varno==0, we
can rewrite those to become varno==1, i.e. use the Vars from the first
UNION child.  This does result in showing Vars from relations that are
not present in the final plan, but that's no different to what we see
when normal base relations are proven dummy.

Without this fix it would be possible to see the following error in
EXPLAIN VERBOSE when all UNION inputs were proven empty.

ERROR:  bogus varno: 0

Author: David Rowley <dgrowleyml@gmail.com>
Discussion: https://postgr.es/m/CAApHDvrUASy9sfULMEsM2udvZJP6AoBRCZvHYXYxZTy2tX9FYw@mail.gmail.com
2025-10-07 14:15:04 +13:00
.github Add CODE_OF_CONDUCT.md, CONTRIBUTING.md, and SECURITY.md. 2024-07-02 13:03:58 -05:00
config Remove traces of support for Sun Studio compiler 2025-09-12 07:39:05 +02:00
contrib Don't include access/htup_details.h in executor/tuptable.h 2025-10-05 18:00:38 +02:00
doc Revert "Improve docs syntax checking" 2025-10-06 07:53:31 -04:00
src Fix incorrect targetlist in dummy UNIONs 2025-10-07 14:15:04 +13:00
.cirrus.star ci: Simplify ci-os-only handling 2025-08-14 12:09:34 -04:00
.cirrus.tasks.yml Revert "Improve docs syntax checking" 2025-10-06 07:53:31 -04:00
.cirrus.yml ci: Per-repo configuration for manually trigger tasks 2025-08-14 11:54:03 -04:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.editorconfig Add script to keep .editorconfig in sync with .gitattributes 2025-02-01 10:09:45 +01:00
.git-blame-ignore-revs Add commit 7e9c216b52 to .git-blame-ignore-revs. 2025-09-13 14:55:38 -05:00
.gitattributes Fix git whitespace warning 2025-08-15 10:32:35 +02:00
.gitignore Update top-level .gitignore. 2022-12-04 15:23:00 -05:00
.mailmap Add a Git .mailmap file 2024-11-05 13:56:02 +01:00
aclocal.m4 autoconf: Move export_dynamic determination to configure 2022-12-06 18:55:28 -08:00
configure Remove traces of support for Sun Studio compiler 2025-09-12 07:39:05 +02:00
configure.ac Remove traces of support for Sun Studio compiler 2025-09-12 07:39:05 +02:00
COPYRIGHT Align organization wording in copyright statement 2025-05-16 11:20:07 -04:00
GNUmakefile.in Allow selecting the git revision to be packaged by "make dist". 2024-05-03 11:08:50 -04:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Remove AIX support 2024-02-28 15:17:23 +04:00
meson.build Fix meson build with -Duuid=ossp when using version older than 0.60 2025-09-22 08:03:23 +09:00
meson_options.txt Add support for basic NUMA awareness 2025-04-07 23:08:17 +02:00
README.md Revise the style of a paragraph in README.md. 2024-03-21 10:16:41 -05:00

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.

Copyright and license information can be found in the file COPYRIGHT.

General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.

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