On Tue, Feb 09, 2021 at 10:54:50AM +0200, Heikki Linnakangas wrote:
> (I may have said this before, but) My overall high-level impression of this
> patch is that it's really cmmplex for a feature that you use maybe once in
> the lifetime of a cluster. I'm happy to review but I'm not planning to
> commit this myself. I don't object if some other committer picks this up
> (Magnus?).
I was just looking at the latest patch set as a matter of curiosity,
and I have a shared feeling. I think that this is a lot of
complication in-core for what would be a one-time operation,
particularly knowing that there are other ways to do it already with
the offline checksum tool, even if that is more costly:
- Involve logical replication after initializing the new instance with
--data-checksums, or in an upgrade scenatio with pg_upgrade.
- Involve physical replication: stop the standby cleanly, enable
checksums on it and do a switchover.
Another thing we could do is to improve pg_checksums with a parallel
mode. The main design question would be how to distribute the I/O,
and that would mean balancing at least across tablespaces.
--
Michael