Horton

Re: pg_verify_checksums and -fno-strict-aliasing

Michael Banck <michael.banck@credativ.de>

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From: Michael Banck <michael.banck@credativ.de>
To: Magnus Hagander <magnus@hagander.net>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: Fabien COELHO <coelho@cri.ensmp.fr>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2018-08-30T20:22:24Z
Lists: pgsql-hackers 
Hi,

Am Donnerstag, den 30.08.2018, 22:02 +0200 schrieb Magnus Hagander:
> PFA some *very* basic tests for pg_verify_checksums, which should at
> least be enough to catch the kind of errors we had now in the tool
> itself.

I proposed something similar for pg_basebackup back then and IIRC Peter
(rightfully) complained that using a system catalog for that wasn't so
great - also, are you sure the relfilenode will always be stable? Then
again, this is obviously a throw-away data directory so it should be no
general issue, just a matter of taste.

https://github.com/credativ/pg_checksums/blob/master/t/001_checksums.pl
has some similar tests at the end but creates a table for corruption,
adds some safeguards for block size and also uses  command_checks_all()
to parse the output. It's PGDG licensed so you're welcome to take some
or all of that.


Michael

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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.