Álvaro Herrera 7b1053a577 doc: mention unusability of dropped CHECK to verify NOT NULL It's possible to use a CHECK (col IS NOT NULL) constraint to skip scanning a table for nulls when adding a NOT NULL constraint on the same column. However, if the CHECK constraint is dropped on the same command that the NOT NULL is added, this fails, i.e., makes the NOT NULL addition slow. The best we can do about it at this stage is to document this so that users aren't taken by surprise. (In Postgres 18 you can directly add the NOT NULL constraint as NOT VALID instead, so there's no longer much use for the CHECK constraint, therefore no point in building mechanism to support the case better.) Reported-by: Andrew <psy2000usa@yahoo.com> Reviewed-by: David G. Johnston <david.g.johnston@gmail.com> Discussion: https://postgr.es/m/175385113607.786.16774570234342968908@wrigleys.postgresql.org		6 months ago
.github	Add CODE_OF_CONDUCT.md, CONTRIBUTING.md, and SECURITY.md.	2 years ago
config	Don't put library-supplied -L/-I switches before user-supplied ones.	6 months ago
contrib	Allow resetting unknown custom GUCs with reserved prefixes.	6 months ago
doc	doc: mention unusability of dropped CHECK to verify NOT NULL	6 months ago
src	Fix assertion failure in pgbench when handling multiple pipeline sync messages.	6 months ago
.cirrus.star	Remove duplicate words in docs and code comments.	2 years ago
.cirrus.tasks.yml	ci: Check for missing dependencies in meson builds	10 months ago
.cirrus.yml	ci: Test NetBSD and OpenBSD	11 months ago
.dir-locals.el	Make Emacs perl-mode indent more like perltidy.	7 years ago
.editorconfig	Add script to keep .editorconfig in sync with .gitattributes	12 months ago
.git-blame-ignore-revs	Add commit `07448b3969` to .git-blame-ignore-revs.	7 months ago
.gitattributes	Add script to keep .editorconfig in sync with .gitattributes	12 months ago
.gitignore	Update top-level .gitignore.	3 years ago
.mailmap	Add a Git .mailmap file	1 year ago
COPYRIGHT	Align organization wording in copyright statement	8 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
Makefile	Adapt REL_18_STABLE to its new status as a stable branch	7 months ago
README.md	Adapt REL_18_STABLE to its new status as a stable branch	7 months ago
aclocal.m4	autoconf: Move export_dynamic determination to configure	3 years ago
configure	Fix ./configure checks with __cpuidex() and __cpuid()	6 months ago
configure.ac	Fix ./configure checks with __cpuidex() and __cpuid()	6 months ago
meson.build	Fix ./configure checks with __cpuidex() and __cpuid()	6 months ago
meson_options.txt	Add support for basic NUMA awareness	10 months ago

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/18/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/18/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/.