Horton

Re: Problem while setting the fpw with SIGHUP

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Amit Kapila <amit.kapila16@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>, Dilip Kumar <dilipbalaut@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2018-04-23T16:21:04Z
Lists: pgsql-hackers 
On Wed, Apr 18, 2018 at 9:49 PM, Michael Paquier <michael@paquier.xyz> wrote:
> On Wed, Apr 18, 2018 at 10:52:51AM -0400, Robert Haas wrote:
>> I would just document the risks.  If the documentation says that you
>> can't rely on the value until after the next checkpoint, or whatever
>> the rule is, then I think we're fine.  I don't think that we really
>> have the infrastructure to do any better; if we try, we'll just end up
>> with odd warts.  Documenting the current set of warts is less churn
>> and less work.
>
> The last version of the patch proposed has eaten this diff which was
> part of one of the past versions (v2-0001-Change-FPW-handling.patch from
> https://www.postgresql.org/message-id/20180412.103430.133595350.horiguchi.kyotaro%40lab.ntt.co.jp):
> +        The default is <literal>on</literal>. The change of the parameter takes
> +        effect at the next checkpoint time.
> So there were some documentation about the beHavior change for what it's
> worth.

Fine, but that doesn't answer the question of whether we actually need
to or should change the behavior in the first place.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Fix assertion failure when updating full_page_writes for checkpointer.

  2. Attach FPI to the first record after full_page_writes is turned on.

  3. Revamp the WAL record format.

  4. Move the backup-block logic from XLogInsert to a new file, xloginsert.c.