Horton

Re: Online enabling of checksums

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Bruce Momjian <bruce@momjian.us>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>, Tom Lane <tgl@sss.pgh.pa.us>, Daniel Gustafsson <daniel@yesql.se>, Robert Haas <robertmhaas@gmail.com>, Magnus Hagander <magnus@hagander.net>, Andrey Borodin <x4mmm@yandex-team.ru>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Michael Banck <michael.banck@credativ.de>, Greg Stark <stark@mit.edu>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2018-08-01T16:55:07Z
Lists: pgsql-hackers 
Hi,

On 2018-08-01 12:45:27 -0400, Bruce Momjian wrote:
> On Wed, Aug  1, 2018 at 09:39:43AM -0700, Andres Freund wrote:
> > On 2018-08-01 12:36:13 -0400, Bruce Momjian wrote:
> > > This patchset is weird because it is perhaps our first case of trying to
> > > change the state of the server while it is running.  We just don't have
> > > an established protocol for how to orchestrate that, so we are limping
> > > along toward a solution.
> > 
> > There's a number of GUCs that do this? Even in related areas,
> > cf. full_page_writes.
> 
> How is that taking the server from one state to the next in a
> non-instantaneous way?

Because it requires coordination around checkpoints, it can only really
fully take effect after the start of a checkpoint.  And it even both has
primary and replica differences...

Greetings,

Andres Freund

Commits

  1. Online enabling and disabling of data checksums

  2. Deactive flapping checksum isolation tests.

  3. Add support for coordinating record typmods among parallel workers.