Re: Gotchas about pg_verify_checksums

Hi Michael,

On Mon, Apr 16, 2018 at 11:30:30AM +0900, Michael Paquier wrote:
> On Thu, Apr 12, 2018 at 05:47:29AM +0900, Michael Paquier wrote:
> > On Wed, Apr 11, 2018 at 10:21:29PM +0200, Daniel Gustafsson wrote:
> >> Naming it pg_checksums, with only verification as an option, seems to me to
> >> imply future direction for 12 more than what pg_verify_checksums does. I would
> >> leave it the way it is, but I don’t have very strong opinions (or any plans on
> >> hacking on offline checksum enabling for that matter).
> >
> > Okay, I am fine to let such decision to you and Magnus at the end as the
> > authors and committers of the thing. I think that I will just hack out
> > this tool myself after reusing this code if you don't mind of course..
>
> If anybody on this list is interested, I have extended
> pg_verify_checksums into this tool I called pg_checksums which is able
> to do a couple of more things like enable checksums, disable checksums,
> bypass the final fsync of the data folder with a --no-sync. The core
> feature to verify checksums is still around of course.
>
> This allows anybody to control the checksums of a cluster that was shut
> down cleanly, which I wanted for some time myself:
> https://github.com/michaelpq/pg_plugins/tree/master/pg_checksums

I didn't see this part of the thread immediately, but following a
discussion with Magnus on offline activation/deactivation of checksums
at PGConf.DE, I independently adapted pg_verify_checksums in a very
similar fashion on my way back from the conference, also renaming it to
pg_checksums etc...

> That's only compatible with v11, but it can be easily tweaked to be
> compatible with past versions. I am of course not proposing to include
> that in v11 or above. If anybody wishes to do a proposal based on that
> stuff for v12, please feel free to.

I think it is useful for legacy installation which "forgot" to enable
checksums when they setup their instances and/or came around that they
are useful in the meantime and are willing to take the downtime in order
to activate them.

So I decided to add some support for earlier version in my version of
the program, and pushed it to https://github.com/credativ/pg_checksums
if anybody is interested in that. I have to admit that it is quite less
fancy than your version.

Michael

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