Horton

Re: Offline enabling/disabling of data checksums

Michael Banck <michael.banck@credativ.de>

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From: Michael Banck <michael.banck@credativ.de>
To: Magnus Hagander <magnus@hagander.net>, Michael Paquier <michael@paquier.xyz>
Cc: Fabien COELHO <coelho@cri.ensmp.fr>, Sergei Kornilov <sk@zsrv.org>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Date: 2019-03-14T15:26:20Z
Lists: pgsql-hackers

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Hi,

Am Donnerstag, den 14.03.2019, 15:26 +0100 schrieb Magnus Hagander:
> Given that the failure is data corruption, I don't think big fat
> warning is enough. We should really make it impossible to start up the
> postmaster by mistake during the checksum generation. People don't
> read the documentation until it's too late. And it might not even be
> under their control - some automated tool might go in and try to start
> postgres, and boom, corruption.

I guess you're right.

> One big-hammer method could be similar to what pg_upgrade does --
> temporarily rename away the controlfile so postgresql can't start, and
> when done, put it back.

That sounds like a good solution to me. I've made PoC patch for that,
see attached.

The only question is whether pg_checksums should try to move pg_control
back (i) on failure (ii) when interrupted?


Michael

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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/