Horton

Re: Offline enabling/disabling of data checksums

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Fabien COELHO <coelho@cri.ensmp.fr>
Cc: Michael Banck <michael.banck@credativ.de>, Postgres hackers <pgsql-hackers@postgresql.org>
Date: 2018-12-27T01:15:34Z
Lists: pgsql-hackers 
On Wed, Dec 26, 2018 at 07:43:17PM +0100, Fabien COELHO wrote:
>> It adds an (now mandatory) --action parameter that takes either verify,
>> enable or disable as argument.
> 
> I'd rather have explicit switches for verify, enable & disable, and verify
> would be the default if none is provided.

Okay, noted for the separate switches.  But I don't agree with the
point of assuming that --verify should be enforced if no switches are
defined.  That feels like a trap for newcomers of this tool..

> For enable/disable, while the command is running, it should mark the cluster
> as opened to prevent an unwanted database start. I do not see where this is
> done.

You have pretty much the same class of problems if you attempt to
start a cluster on which pg_rewind or the existing pg_verify_checksums
is run after these have scanned the control file to make sure that
they work on a cleanly-stopped instance.  In short, this is a deal
between code simplicity and trying to have the tool outsmart users in
the way users use the tool.  I tend to prefer keeping the code simple
and not worry about cases where the users mess up with their
application, as there are many more things which could go wrong.
--
Michael

Commits

  1. Reorganize Notes section in documentation of pg_checksums

  2. Add option -N/--no-sync to pg_checksums

  3. Add options to enable and disable checksums in pg_checksums

  4. Refactor more code logic to update the control file

  5. Rename pg_verify_checksums to pg_checksums

  6. Fix cross-version compatibility checks of pg_verify_checksums

  7. Add routine able to update the control file to src/common/