public inbox for [email protected]  

help / color / mirror / Atom feed

From: Noah Misch <[email protected]>
To: [email protected]
Subject: pg_waldump vs. all-zeros WAL files; server creation of such files
Date: Sat, 12 Aug 2023 20:15:31 -0700
Message-ID: <[email protected]> (raw)

The attached 010_zero.pl, when run as part of the pg_waldump test suite, fails
at today's master (c36b636) and v15 (1bc19df).  It passes at v14 (5a32af3).
Command "pg_waldump --start 0/01000000 --end 0/01000100" fails as follows:

  pg_waldump: error: WAL segment size must be a power of two between 1 MB and 1 GB, but the WAL file "000000010000000000000002" header specifies 0 bytes

Where it fails, the server has created an all-zeros WAL file under that name.
Where it succeeds, that file doesn't exist at all.  Two decisions to make:

- Should a clean server shutdown ever leave an all-zeros WAL file?  I think
  yes, it's okay to let that happen.
- Should "pg_waldump --start $X --end $Y" open files not needed for the
  requested range?  I think no.

Bisect of master got:
30a53b7 Wed Mar 8 16:56:37 2023 +0100 Allow tailoring of ICU locales with custom rules
Doesn't fail at $(git merge-base REL_15_STABLE master).  Bisect of v15 got:
811203d Sat Aug 6 11:50:23 2022 -0400 Fix data-corruption hazard in WAL-logged CREATE DATABASE.

I suspect those are innocent.  They changed the exact WAL content, which I
expect somehow caused creation of segment 2.

Oddly, I find only one other report of this:
https://www.postgresql.org/message-id/CAJ6DU3HiJ5FHbqPua19jAD%3DwLgiXBTjuHfbmv1jCOaNOpB3cCQ%40mail.g...

Thanks,
nm


Attachments:

  [application/x-perl] 010_zero.pl (545B, ../[email protected]/2-010_zero.pl)
  download

view thread (3+ messages)  latest in thread

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected]
  Subject: Re: pg_waldump vs. all-zeros WAL files; server creation of such files
  In-Reply-To: <[email protected]>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox