From: Andrew Dunstan <andrew@dunslane.net>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: pg_waldump: Add support for reading WAL from tar archives
Date: Fri, 20 Mar 2026 19:32:10 +0000
Message-ID: <E1w3fZp-000gjc-2w@gemulon.postgresql.org> (raw)
pg_waldump: Add support for reading WAL from tar archives
pg_waldump can now accept the path to a tar archive (optionally
compressed with gzip, lz4, or zstd) containing WAL files and decode
them. This was added primarily for pg_verifybackup, which previously
had to skip WAL parsing for tar-format backups.
The implementation uses the existing archive streamer infrastructure
with a hash table to track WAL segments read from the archive. If WAL
files within the archive are not in sequential order, out-of-order
segments are written to a temporary directory (created via mkdtemp under
$TMPDIR or the archive's directory) and read back when needed. An
atexit callback ensures the temporary directory is cleaned up.
The --follow option is not supported when reading from a tar archive.
Author: Amul Sul <sulamul@gmail.com>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Jakub Wartak <jakub.wartak@enterprisedb.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Euler Taveira <euler@eulerto.com>
Reviewed-by: Andrew Dunstan <andrew@dunslane.net>
Reviewed-by: Zsolt Parragi <zsolt.parragi@percona.com>
discussion: https://postgr.es/m/CAAJ_b94bqdWN3h2J-PzzzQ2Npbwct5ZQHggn_QoYGhC2rn-=WQ@mail.gmail.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/b15c1513984e6eafd264bf6e84a08549905621f1
Modified Files
--------------
doc/src/sgml/ref/pg_waldump.sgml | 23 +-
src/bin/pg_waldump/Makefile | 7 +-
src/bin/pg_waldump/archive_waldump.c | 860 +++++++++++++++++++++++++++++++++++
src/bin/pg_waldump/meson.build | 4 +-
src/bin/pg_waldump/pg_waldump.c | 288 +++++++++---
src/bin/pg_waldump/pg_waldump.h | 51 +++
src/bin/pg_waldump/t/001_basic.pl | 264 ++++++++---
src/tools/pgindent/typedefs.list | 4 +
8 files changed, 1364 insertions(+), 137 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: andrew@dunslane.net, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: pg_waldump: Add support for reading WAL from tar archives
In-Reply-To: <E1w3fZp-000gjc-2w@gemulon.postgresql.org>
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