Re: pg_waldump: support decoding of WAL inside tarfile

On Wed, Mar 18, 2026 at 8:46 PM Amul Sul <sulamul(at)gmail(dot)com> wrote:
>
> On Wed, Mar 18, 2026 at 5:15 PM Amul Sul <sulamul(at)gmail(dot)com> wrote:
> >
> > On Wed, Mar 11, 2026 at 10:38 PM Andrew Dunstan <andrew(at)dunslane(dot)net> wrote:
> > > [...]
> > > Looks pretty good. I have squashed them into three patches I think are committable. Also attached is a diff showing what's changed - mainly this:
> > >
> > > . --follow + tar archive rejected (pg_waldump.c) — new validation prevents a confusing pg_fatal when combining --follow with a tar archive
> > > . error messages split (archive_waldump.c) — the single "could not read file" error is now two distinct messages: "WAL segment is too short" (truncated file) vs "unexpected end of archive" (archive EOF) - Fixes an issue raised in review
> > > . hash table cleanup (archive_waldump.c) — free_archive_reader now iterates and frees all remaining hash entries and destroys the table
> > >
> >
> > The final squashed version looks good to me, thank you. But, I would
> > like to propose splitting the 0001 patch into two separate commits: a
> > preparatory refactoring of the pg_waldump code and a standalone commit
> > that moves the tar archive detection and compression logic to a common
> > location, as the latter is an independent improvement to the existing
> > codebase. Additionally, since the test file refactoring was only kept
> > separate to facilitate the review and has already been reviewed, I
> > suggest merging those changes into the main feature patch i.e. 0002.
> > All other elements should remain in a single preparatory refactoring
> > patch for pg_waldump.
> >
> > Attached is the version that includes the proposed split. No
> > additional changes to 0002 and 0003 patches.
> >
>
> Added the two missing 'Reviewed-by' lines to the credit section of the
> commit message and did a minor optimization in get_archive_wal_entry.
>

Attaching an updated version. It includes some tweaks to code
comments, adds an assert inside get_archive_wal_entry(), moves the
archive_read_buf_size declaration and usage into an assert-enabled
check, and makes a minor change to precheck_tar_backup_file() to
assign out-variables only after successful validation.

Regards,
Amul