Re: pg_waldump: support decoding of WAL inside tarfile

Tomas Vondra <tomas(at)vondra(dot)me> writes:
> On 3/28/26 23:36, Tom Lane wrote:
>> It's apparently been there and been default since FreeBSD 13.1.
>> This leads one to wonder how come BF member dikkop is managing
>> to run this test successfully. I speculate that it's using a
>> filesystem type that doesn't do sparse files (cc'ing Vondra
>> for confirmation on that).

> It's running on ufs. But I think the explanation is very simple. We had
> a short power outage on Thursday, and the FreeBSD machine failed to boot
> properly after the power was restored. IIUC this test is new, right?

Not that new, it dates to b15c15139, about a week ago.

I've reproduced Thomas' failure on a local FreeBSD 15.0 image
using zfs, and confirmed that this cowboy hack fixes it:

diff --git a/src/bin/pg_waldump/t/001_basic.pl b/src/bin/pg_waldump/t/001_basic.pl
index 8bb8fa225f6..2904f4ef118 100644
--- a/src/bin/pg_waldump/t/001_basic.pl
+++ b/src/bin/pg_waldump/t/001_basic.pl
@@ -346,7 +346,7 @@ sub generate_archive
# move into the WAL directory before archiving files
my $cwd = getcwd;
chdir($directory) || die "chdir: $!";
- command_ok([$tar, $compression_flags, $archive, @files]);
+ command_ok([$tar, $compression_flags, $archive, '--no-read-sparse', @files]);
chdir($cwd) || die "chdir: $!";
}

Of course we can't commit that, but maybe somebody wants to
product-ize it. (Not me, at least not today.)

regards, tom lane