Re: Fix safe_wal_size for slots without restart_lsn

On Thu, May 28, 2026 at 9:01 AM Xuneng Zhou <xunengzhou(at)gmail(dot)com> wrote:
>
> On Wed, May 27, 2026 at 6:55 PM Xuneng Zhou <xunengzhou(at)gmail(dot)com> wrote:
> >
> > Hi,
> >
> > Currently, pg_replication_slots can report a non-null safe_wal_size
> > for a replication slot that has never reserved WAL, if
> > max_slot_wal_keep_size is finite.
> >
> > Such a slot has restart_lsn = NULL and wal_status = NULL. safe_wal_size is
> > derived from restart_lsn, so it's not meaningful in this state. The
> > current code handles WALAVAIL_REMOVED but not WALAVAIL_INVALID_LSN
> > before computing safe_wal_size, leading arithmetic on InvalidXLogRecPtr.
> >
> > Fix this by returning NULL for safe_wal_size when WAL availability is
> > WALAVAIL_INVALID_LSN.
> >
>
> Fixed the indentation issue in v1 and updated the comment and doc. Not
> sure this small issue warrants an additional test, still added one in
> case someone wants it.

Improved the readability of the new test.

--
Regards,
Xuneng Zhou
HighGo Software Co., Ltd.