Horton

Re: pg_verify_checksums and -fno-strict-aliasing

Michael Paquier <michael@paquier.xyz>

View thread View on postgr.es
From: Michael Paquier <michael@paquier.xyz>
To: Magnus Hagander <magnus@hagander.net>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Fabien COELHO <coelho@cri.ensmp.fr>, Michael Banck <michael.banck@credativ.de>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2018-08-30T22:44:58Z
Lists: pgsql-hackers 
On Thu, Aug 30, 2018 at 10:07:38PM +0200, Magnus Hagander wrote:
> I wonder if your tests that pg_control has picked things up belong more in
> the tests of initdb itself?

For the case where checksums are disabled, moving there the check on
control data makes sense.

> Do you think there is value in testing against a non-checksum cluster? I
> guess there's some point to it. I think testing actual corruption (like my
> version of the tests) is more valuable, but perhaps we should just do both?

Yeah, let's do stuff on a single cluster which has them only enabled,
as initializing a node is one of the most costly operations in TAP
tests.  Checking that the server is stopped is definitely a must in my
opinion, and your addition about emulating corrupted blocks is a good
idea.  I would personally vote for keeping a control file check within
the tests of pg_verify_checksums as that's cheap.
--
Michael

Commits

  1. Avoid using potentially-under-aligned page buffers.

  2. Code review for pg_verify_checksums.c.

  3. Make checksum_impl.h safe to compile with -fstrict-aliasing.