Tom Lane f25a07b2d9 Make pg_mkdir_p() tolerant of a concurrent directory creation. pg_mkdir_p creates each missing path component with a stat() followed by mkdir(). If the stat() reports the component as absent but another process creates it in the window before this process's mkdir(), mkdir() fails with EEXIST and pg_mkdir_p treated that as a hard error -- unlike "mkdir -p", which is meant to be idempotent and race-tolerant. This shows up when several processes concurrently create paths that share an ancestor directory: for example, parallel initdb runs whose data directories live under a common temporary directory. One process wins the race to create the shared ancestor and the others fail with could not create directory "...": File exists Fix this race condition by first trying mkdir() and only attempting stat() if it fails with EEXIST. On Windows, there's an additional problem: stat() opens a file handle and participates in share-mode locking, which means it can transiently fail on a directory another process is concurrently creating. Use GetFileAttributes() instead: it requests only FILE_READ_ATTRIBUTES and is exempt from share-mode denial, so it reliably sees a concurrently-created directory. I (tgl) also chose to back-patch 039f7ee0f's effects on this function, so that pgmkdirp.c remains identical in all live branches. Author: Andrew Dunstan <andrew@dunslane.net> Co-authored-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/3ca004de-e49b-4471-b8aa-fd656e70f68c@dunslane.net Backpatch-through: 14		1 day ago
.github	ci: Improve ccache handling	2 weeks ago
config	Update config.guess and config.sub	2 months ago
contrib	hstore_plperl: Add CHECK_FOR_INTERRUPTS() in reference-unwinding loop.	2 days ago
doc	doc PG 19 relnotes: fix "standard_conforming_strings = off text	2 days ago
src	Make pg_mkdir_p() tolerant of a concurrent directory creation.	1 day ago
.dir-locals.el	Make Emacs perl-mode indent more like perltidy.	8 years ago
.editorconfig	Update .editorconfig and .gitattributes for postgresql.conf.sample.	7 months ago
.git-blame-ignore-revs	Add previous commit to .git-blame-ignore-revs.	2 weeks ago
.gitattributes	Update .editorconfig and .gitattributes for postgresql.conf.sample.	7 months ago
.gitignore	Update top-level .gitignore.	4 years ago
.mailmap	Add a Git .mailmap file	2 years ago
COPYRIGHT	Update copyright for 2026	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
Makefile	Restore AIX support.	4 months ago
README.md	Revise the style of a paragraph in README.md.	2 years ago
aclocal.m4	autoconf: Move export_dynamic determination to configure	4 years ago
configure	Stamp 19beta1.	3 weeks ago
configure.ac	Stamp 19beta1.	3 weeks ago
meson.build	Stamp 19beta1.	3 weeks ago
meson_options.txt	Revert "Add built-in fuzzing harnesses for security testing."	2 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/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/.