Horton

Re: prevent immature WAL streaming

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Andrew Dunstan <andrew@dunslane.net>, "Bossart, Nathan" <bossartn@amazon.com>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, "masao.fujii@oss.nttdata.com" <masao.fujii@oss.nttdata.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>, "mengjuan.cmj@alibaba-inc.com" <mengjuan.cmj@alibaba-inc.com>, "Jakub.Wartak@tomtom.com" <Jakub.Wartak@tomtom.com>, Ryo Matsumura <matsumura.ryo@fujitsu.com>
Date: 2021-10-13T19:13:45Z
Lists: pgsql-hackers 
Hi,

On 2021-10-13 15:52:46 -0300, Alvaro Herrera wrote:
> > Hm. I guess we can disable autovac. But that's not a great solution, there
> > might be WAL files due to catalog access etc too.
> 
> Well, we don't expect anything else to happen -- the cluster is
> otherwise idle.  I think we should do it regardless of any other
> changes, just to keep things steadier.

IDK, it seems good to have a bit of variance as well. But I don't have a
strong opinion on it.


> > Another thing: filling a segment by inserting lots of very tiny rows is pretty
> > expensive. Can't we use something a bit wider? Perhaps even emit_message?

FWIW, the count of inserted rows is something like 171985 ;)


> I think I realized partway through writing the test that I could use
> emit_message instead of using a batched row insert ... so, yeah, we
> can use it here also.

Cool. Even if we want to use inserts, lets at least make the rows wide...

I think it'd be good to have a bit of variance in record width. So perhaps
adding a bit of random() in to influence record width would be a good idea?

Greetings,

Andres Freund

Commits

  1. Fix determination of broken LSN in OVERWRITTEN_CONTRECORD

  2. Fix instability in 026_overwrite_contrecord.pl test.

  3. Fix typo

  4. Change recently added test code for stability

  5. Remove unstable, unnecessary test; fix typo

  6. Repair two portability oversights of new test

  7. Fix WAL replay in presence of an incomplete record

  8. Document XLOG_INCLUDE_XID a little better

  9. Revert "Avoid creating archive status ".ready" files too early"

  10. Avoid creating archive status ".ready" files too early

  11. Fix scenario where streaming standby gets stuck at a continuation record.

  12. Teach xlogreader to follow timeline switches

  13. Forbid using pg_xlogfile_name() and pg_xlogfile_name_offset() during