Horton

Re: Offline enabling/disabling of data checksums

Sergei Kornilov <sk@zsrv.org>

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From: Sergei Kornilov <sk@zsrv.org>
To: Magnus Hagander <magnus@hagander.net>
Cc: Michael Paquier <michael@paquier.xyz>, Fabien COELHO <coelho@cri.ensmp.fr>, Michael Banck <michael.banck@credativ.de>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Date: 2019-03-13T11:40:11Z
Lists: pgsql-hackers 
Hi

>> One new question from me: how about replication?
>> Case: primary+replica, we shut down primary and enable checksum, and "started streaming WAL from primary" without any issue. I have master with checksums, but replica without.
>> Or cluster with checksums, then disable checksums on primary, but standby think we have checksums.
>
> Enabling or disabling the checksums offline on the master quite clearly requires a rebuild of the standby, there is no other way (this is one of the reasons for the online enabling in that patch, so I still hope we can get that done -- but not for this version).

I mean this should be at least documented.
Change system id... Maybe is reasonable

>> Also we support ./configure --with-blocksize=(not equals 8)? make check on HEAD fails for me. If we support this - i think we need recheck BLCKSZ between compiled pg_checksum and used in PGDATA
>
> You mean if the backend and pg_checksums is built with different blocksize? Yeah, that sounds like something which is a cheap check and should be done.

Yep

regards, Sergei

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/