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Re: pg_waldump: support decoding of WAL inside tarfile

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>, Michael Paquier <michael@paquier.xyz>, Andrew Dunstan <andrew@dunslane.net>, Amul Sul <sulamul@gmail.com>, Zsolt Parragi <zsolt.parragi@percona.com>, Robert Haas <robertmhaas@gmail.com>, Chao Li <li.evan.chao@gmail.com>, Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>, Fujii Masao <masao.fujii@gmail.com>, Jakub Wartak <jakub.wartak@enterprisedb.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-03-28T22:08:43Z
Lists: pgsql-hackers 
On Sun, Mar 29, 2026 at 10:49 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Huh.  What is your platform exactly?  Maybe more to the point,
> what is the tar program you're using?

FreeBSD tar 3.8.2.

> > Seems like it already stepped over 000000010000000000000002 earlier?
> > Could it be a table-of-contents order dependency bug or something like
> > that?
>
> If you look at the TAP script, you'll see that it tries to randomize
> the order of the entries in the tar file (see sub generate_archive).
> So if that's the problem, it shouldn't reproduce 100%, and also we
> should be seeing lots of freckles on the buildfarm.  We're not, so
> there must be something off-the-beaten-track about your test
> environment.

Right, I see now.  There is something different about
000000010000000000000002 though: it doesn't seem to have a normal
(non-PAX, non-GNU) TOC entry, unlike000000010000000000000001.  Trying
to figure out why...

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Use size_t instead of Size in pg_waldump

  2. More tar portability adjustments.

  3. Further harden tests that might use not-so-compatible tar versions.

  4. Harden astreamer tar parsing logic against archives it can't handle.

  5. Fix pg_waldump/t/001_basic.pl with BSD tar on ZFS.

  6. Remove a low-value, high-risk optimization in pg_waldump.

  7. Fix misuse of simplehash.h hash operations in pg_waldump.

  8. Fix file descriptor leakages in pg_waldump.

  9. Fix poorly-sized buffers in astreamer compression modules.

  10. Remove read_archive_file()'s "count" parameter.

  11. Report detailed errors from XLogFindNextRecord() failures.

  12. Fix assorted bugs in archive_waldump.c.

  13. Remove nonfunctional tar file trailer size check.

  14. Fix finalization of decompressor astreamers.

  15. Move tar detection and compression logic to common.

  16. pg_verifybackup: Enable WAL parsing for tar-format backups

  17. pg_waldump: Add support for reading WAL from tar archives

  18. pg_waldump: Preparatory refactoring for tar archive WAL decoding.

  19. pg_waldump: Remove file-level global WalSegSz.

  20. pg_verifybackup: Verify tar-format backups.