Re: pg_waldump: support decoding of WAL inside tarfile

Hi,

On 2026-03-24 12:11:44 +0900, Michael Paquier wrote:
> On Sun, Mar 22, 2026 at 11:02:20PM -0400, Tom Lane wrote:
> > Proposed patch attached. There might be an argument for using some
> > other size than 256K for the other two decompressors, but my
> > inclination is to try to make all three use roughly the same block
> > size. (See also 66ec01dc4.)
>
> The buildfarm has switched mostly to green, except on this one:
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=hoatzin&dt=2026-03-23%2006%3A00%3A42

I think there's a few more failues. Fairywren regularly fails, including in a
run from today.

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=fairywren&dt=2026-03-25%2003%3A48%3A06

There also are a lot of CI failures. E.g.

https://cirrus-ci.com/task/6153854431002624
https://api.cirrus-ci.com/v1/artifact/task/6153854431002624/testrun/build/testrun/pg_waldump/001_basic/log/regress_log_001_basic
# Running: pg_waldump --path C:\msys64\tmp\tNfU5IfQ4a/pg_wal.tar.gz --start 0/01806F48 --end 0/03093BD8
[22:46:25.358](3.991s) not ok 160 - runs with path option and start and end locations: exit code 0
[22:46:25.363](0.005s) # Failed test 'runs with path option and start and end locations: exit code 0'
# at C:/cirrus/src/bin/pg_waldump/t/001_basic.pl line 399.
[22:46:25.364](0.001s) ok 161 - runs with path option and start and end locations: no stderr
[22:46:25.365](0.001s) not ok 162 - runs with path option and start and end locations: matches
[22:46:25.365](0.000s) # Failed test 'runs with path option and start and end locations: matches'
# at C:/cirrus/src/bin/pg_waldump/t/001_basic.pl line 399.
[22:46:25.366](0.000s) # ''
# doesn't match '(?^:.)'

I was first suspecting that this is due to

commit 1c162c965a1
Author: Fujii Masao <fujii(at)postgresql(dot)org>
Date: 2026-03-24 22:33:09 +0900

Report detailed errors from XLogFindNextRecord() failures.

but there are afaict failures from before that:
https://cirrus-ci.com/task/5501609960013824
which is for 4019f725f5d, preceding 1c162c965a1
and
https://cirrus-ci.com/task/5317196043255808

It does feel however the failure frequency has increased substantially:
https://cirrus-ci.com/github/postgres/postgres/master

Greetings,

Andres Freund