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Michael Paquier 909b449e00 Fix concurrency issues with WAL segment recycling on Windows
This commit is mostly a revert of aaa3aed, that switched the routine
doing the internal renaming of recycled WAL segments to use on Windows a
combination of CreateHardLinkA() plus unlink() instead of rename().  As
reported by several users of Postgres 13, this is causing concurrency
issues when manipulating WAL segments, mostly in the shape of the
following error:
LOG:  could not rename file "pg_wal/000000XX000000YY000000ZZ":
Permission denied

This moves back to a logic where a single rename() (well, pgrename() for
Windows) is used.  This issue has proved to be hard to hit when I tested
it, facing it only once with an archive_command that was not able to do
its work, so it is environment-sensitive.  The reporters of this issue
have been able to confirm that the situation improved once we switched
back to a single rename().  In order to check things, I have provided to
the reporters a patched build based on 13.2 with aaa3aed reverted, to
test if the error goes away, and an unpatched build of 13.2 to test if
the error still showed up (just to make sure that I did not mess up my
build process).

Extra thanks to Fujii Masao for pointing out what looked like the
culprit commit, and to all the reporters for taking the time to test
what I have sent them.

Reported-by: Andrus, Guy Burgess, Yaroslav Pashinsky, Thomas Trenz
Reviewed-by: Tom Lane, Andres Freund
Discussion: https://postgr.es/m/3861ff1e-0923-7838-e826-094cc9bef737@hot.ee
Discussion: https://postgr.es/m/16874-c3eecd319e36a2bf@postgresql.org
Discussion: https://postgr.es/m/095ccf8d-7f58-d928-427c-b17ace23cae6@burgess.co.nz
Discussion: https://postgr.es/m/16927-67c570d968c99567%40postgresql.org
Discussion: https://postgr.es/m/YFBcRbnBiPdGZvfW@paquier.xyz
Backpatch-through: 13
2021-03-22 14:02:26 +09:00
config Update copyright for 2021 2021-01-02 13:06:25 -05:00
contrib Allow configurable LZ4 TOAST compression. 2021-03-19 15:10:38 -04:00
doc Provide recovery_init_sync_method=syncfs. 2021-03-20 12:07:28 +13:00
src Fix concurrency issues with WAL segment recycling on Windows 2021-03-22 14:02:26 +09:00
.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
.gitattributes gitattributes: Add new file 2019-11-12 08:13:55 +01:00
.gitignore Support for optimizing and emitting code in LLVM JIT provider. 2018-03-22 11:05:22 -07:00
COPYRIGHT Update copyright for 2021 2021-01-02 13:06:25 -05:00
GNUmakefile.in Make install-tests target work with vpath builds 2020-05-31 18:33:00 -04:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Don't unset MAKEFLAGS in non-GNU Makefile. 2019-06-25 09:36:21 +12:00
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
aclocal.m4 Remove configure-time probe for DocBook DTD. 2020-11-30 15:24:13 -05:00
configure Bring configure support for LZ4 up to snuff. 2021-03-21 17:20:17 -04:00
configure.ac Bring configure support for LZ4 up to snuff. 2021-03-21 17:20:17 -04:00

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/.