Re: more descriptive message for process termination due to max_slot_wal_keep_size

At Tue, 14 Dec 2021 19:31:21 +0530, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> wrote in 
> On Tue, Dec 14, 2021 at 9:35 AM Kyotaro Horiguchi
> <horikyota.ntt@gmail.com> wrote:
> > > [17605] LOG:  terminating process 17614 to release replication slot "s1"
> > + [17605] DETAIL:  The slot's restart_lsn 0/2C0000A0 exceeds max_slot_wal_keep_size.
> > > [17614] FATAL:  terminating connection due to administrator command
> > > [17605] LOG:  invalidating slot "s1" because its restart_lsn 0/2C0000A0 exceeds max_slot_wal_keep_size
> >
> > Somewhat the second and fourth lines look inconsistent each other but
> > that wouldn't be such a problem.  I don't think we want to concatenate
> > the two lines together as the result is a bit too long.
> >
> > > LOG:  terminating process 17614 to release replication slot "s1" because it's restart_lsn 0/2C0000A0 exceeds max_slot_wal_keep_size.
> >
> > What do you think about this?
> 
> Agree. I think we should also specify the restart_lsn value which
> would be within max_slot_wal_keep_size for better understanding.

Thanks!  It seems to me the main message of the "invalidating" log has
no room for further detail.  So I split the reason out to DETAILS line
the same way with the "terminating" message in the attached second
patch. (It is separated from the first patch just for review) I
believe someone can make the DETAIL message simpler or more natural.

The attached patch set emits the following message.

> LOG:  invalidating slot "s1"
> DETAIL:  The slot's restart_lsn 0/10000D68 is behind the limit 0/11000000 defined by max_slot_wal_keep_size.

The second line could be changed like the following or anything other.

> DETAIL:  The slot's restart_lsn 0/10000D68 got behind the limit 0/11000000 determined by max_slot_wal_keep_size.
.....

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center