Horton

Re: Online enabling of checksums

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Magnus Hagander <magnus@hagander.net>
Cc: Andres Freund <andres@anarazel.de>, Andrey Borodin <x4mmm@yandex-team.ru>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Daniel Gustafsson <daniel@yesql.se>, Michael Banck <michael.banck@credativ.de>, Greg Stark <stark@mit.edu>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2018-07-26T17:03:39Z
Lists: pgsql-hackers 
On Tue, Jun 26, 2018 at 7:45 AM, Magnus Hagander <magnus@hagander.net> wrote:
> PFA an updated version of the patch for the next CF. We believe this one
> takes care of all the things pointed out so far.
>
> For this version, we "implemented" the MegaExpensiveRareMemoryBarrier() by
> simply requiring a restart of PostgreSQL to initiate the conversion
> background. That is definitely going to guarantee a memory barrier. It's
> certainly not ideal, but restarting the cluster is still a *lot* better than
> having to do the entire conversion offline. This can of course be improved
> upon in the future, but for now we stuck to the safe way.

Honestly, I feel like the bar for this feature ought to be higher than that.

(I half-expect a vigorous discussion of whether I have set the bar for
the features I've developed in the right place or not, but I think
that's not really a fair response.  If somebody thinks some feature I
implemented should've been more baked, they might be right, but that's
not what this thread is about.  I'm giving you MY opinion about THIS
patch, nothing more or less.)

Why can't we do better?

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

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.