Horton

Re: prevent immature WAL streaming

Alvaro Herrera <alvherre@alvh.no-ip.org>

View thread View on postgr.es
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: "Bossart, Nathan" <bossartn@amazon.com>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>, "andres@anarazel.de" <andres@anarazel.de>, "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>
Date: 2021-09-17T21:22:00Z
Lists: pgsql-hackers 
On 2021-Sep-17, Bossart, Nathan wrote:

> > That was the first implementation, a few versions of the patch ago.  An
> > added benefit of a separate WAL record is that you can carry additional
> > data for validation, such as -- as suggested by Andres -- the CRC of the
> > partial data contained in the message that we're skipping.  I didn't
> > implement that, but it should be trivial to add it.
> 
> I see.  IMO feels a bit counterintuitive to validate a partial record
> that you are ignoring anyway, but I suppose it's still valuable to
> know when the WAL is badly broken.  It's not expensive, and it doesn't
> add a ton of complexity, either.

Yeah, we don't have any WAL record history validation other than the
verifying the LSN of the previous record; I suppose in this particular
case you could argue that we shouldn't bother with any validation
either.  But it seems safer to do it.  It doesn't hurt anything anyway.

-- 
Álvaro Herrera              Valdivia, Chile  —  https://www.EnterpriseDB.com/

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