Re: Replication slot stats misgivings

On Wed, May 12, 2021 at 6:32 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> Amit Kapila <amit.kapila16@gmail.com> writes:
> > I have closed this open item.
>
> That seems a little premature, considering that the
> contrib/test_decoding/sql/stats.sql test case is still failing regularly.

Thank you for reporting.

Ugh, since by commit 592f00f8de we send slot stats every after
spil/stream it’s possible that we report slot stats that have non-zero
counters for spill_bytes/txns and zeroes for total_bytes/txns. It
seems to me it’s legitimate that the slot stats view shows non-zero
values for spill_bytes/txns and zero values for total_bytes/txns
during decoding a large transaction. So I think we can fix the test
script so that it checks only spill_bytes/txns when checking spilled
transactions.

For the record, during streaming transactions, IIUC this kind of thing
doesn’t happen since we update both total_bytes/txns and
stream_bytes/txns before reporting slot stats.

I've attached a patch to fix it.

Regards,


--
Masahiko Sawada
EDB:  https://www.enterprisedb.com/