Horton

Re: Replication slot stats misgivings

Amit Kapila <amit.kapila16@gmail.com>

View thread View on postgr.es
From: Amit Kapila <amit.kapila16@gmail.com>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: vignesh C <vignesh21@gmail.com>, Andres Freund <andres@anarazel.de>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>
Date: 2021-04-22T10:54:54Z
Lists: pgsql-hackers 
On Thu, Apr 22, 2021 at 1:02 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>

Thanks, it looks good to me now. I'll review/test some more before
committing but at this stage, I would like to know from Andres or
others whether they see any problem with this approach to fixing a few
of the problems reported in this thread. Basically, it will fix the
cases where the drop message is lost and we were not able to record
stats for new slots and writing beyond the end of the array when after
restarting the number of slots whose stats are stored in the stats
file exceeds max_replication_slots.

It uses HTAB instead of an array to record slot stats and also taught
pgstat_vacuum_stat() to search for all the dead replication slots in
stats hashtable and tell the collector to remove them. This still uses
slot_name as the key because we were not able to find a better way to
use slot's idx.

Andres, unless you see any problems with this approach, I would like
to move forward with this early next week?

-- 
With Regards,
Amit Kapila.

Commits

  1. Doc: Update logical decoding stats information.

  2. Fix tests for replication slots stats.

  3. Update replication statistics after every stream/spill.

  4. Fix the computation of slot stats for 'total_bytes'.

  5. Another try to fix the test case added by commit f5fc2f5b23.

  6. Use HTAB for replication slot statistics.

  7. Fix test case added by commit f5fc2f5b23.

  8. Add information of total data processed to replication slot stats.

  9. Use NameData datatype for slotname in stats.