David Rowley eaa159632d Fix UNION planner estimate_num_groups with varno==0 `03d40e4b5` added code to provide better row estimates for when a UNION query ended up only with a single child due to other children being found to be dummy rels. In that case, ordinarily it would be ok to call estimate_num_groups() on the targetlist of the only child path, however that's not safe to do if the UNION child is the result of some other set operation as we generate targetlists containing Vars with varno==0 for those, which estimate_num_groups() can't handle. This could lead to: ERROR: XX000: no relation entry for relid 0 Fix this by avoiding doing this when the only child is the result of another set operation. In that case we'll fall back on the assume-all-rows-are-unique method. Reported-by: Alexander Lakhin <exclusion@gmail.com> Author: David Rowley <dgrowleyml@gmail.com> Discussion: https://postgr.es/m/cfbc99e5-9d44-4806-ba3c-f36b57a85e21@gmail.com		10 hours ago
.github	Add CODE_OF_CONDUCT.md, CONTRIBUTING.md, and SECURITY.md.	1 year ago
config	Remove traces of support for Sun Studio compiler	2 months ago
contrib	postgres_fdw: Add more test coverage for EvalPlanQual testing.	10 hours ago
doc	Doc: use uppercase keywords in SQLs	10 hours ago
src	Fix UNION planner estimate_num_groups with varno==0	10 hours ago
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.cirrus.tasks.yml	ci: Add missing "set -e" to scripts run by su.	13 hours ago
.cirrus.yml	ci: Per-repo configuration for manually trigger tasks	3 months ago
.dir-locals.el	Make Emacs perl-mode indent more like perltidy.	7 years ago
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.git-blame-ignore-revs	Add previous commit to .git-blame-ignore-revs.	2 weeks ago
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.mailmap	Add a Git .mailmap file	1 year ago
COPYRIGHT	Align organization wording in copyright statement	6 months ago
GNUmakefile.in	Allow selecting the git revision to be packaged by "make dist".	2 years ago
HISTORY	Canonicalize some URLs	6 years ago
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README.md	Revise the style of a paragraph in README.md.	2 years ago
aclocal.m4	autoconf: Move export_dynamic determination to configure	3 years ago
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README.md

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.

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/.