Re: pg_checksums (or checksums in general) vs tableam

On Wed, Jul 10, 2019 at 3:05 PM Michael Paquier <michael(at)paquier(dot)xyz> wrote:

> On Wed, Jul 10, 2019 at 11:42:34AM +0200, Magnus Hagander wrote:
> > pg_checksums enumerate the files. What if there are files there from a
> > different tableam? Isn't pg_checksums just going to badly fail then,
> since
> > it assumes everything is heap?
> >
> > Also, do we allow AMs that don't support checksumming data? Do we have
> any
> > checks for tables created with such AMs in a system that has checksums
> > enabled?
>
> Table AMs going through shared buffers and smgr.c, like zedstore,
> share the same page header, meaning that the on-disk file is the same
> as heap, and that checksums are compiled similarly to heap.
> pg_checksums is not going to complain on those ones and would work
> just fine.

> Table AMs using their own storage layer (which would most likely use
> their own checksum method normally?) would be ignored by pg_checksums
> if the file names don't match what smgr uses, but it could result in
> failures if they use on-disk file names which match.
>

That would be fine, if we actually knew. Should we (or have we already?)
defined a rule that they are not allowed to use the same naming standard
unless they have the same type of header?

--
Magnus Hagander
Me: https://www.hagander.net/ <http://www.hagander.net/>
Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>