Re: better page-level checksums

On Mon, Jun 13, 2022 at 02:44:41PM -0700, Peter Geoghegan wrote:
> On Fri, Jun 10, 2022 at 6:16 AM Robert Haas <robertmhaas@gmail.com> wrote:
> > > My preference is for an approach that builds on that, or at least
> > > doesn't significantly complicate it. So a cryptographic hash or nonce
> > > can go in the special area proper (structs like BTPageOpaqueData don't
> > > need any changes), but at a page offset before the special area proper
> > > -- not after.
> > >
> > > What disadvantages does that approach have, if any, from your point of view?
> >
> > I think it would be an extremely good idea to store the extended
> > checksum at the same offset in every page. Right now, code that wants
> > to compute checksums, or a tool like pg_checksums that wants to verify
> > them, can find the checksum without needing to interpret any of the
> > remaining page contents. Things get sticky if you have to interpret
> > the page contents to locate the checksum that's going to tell you
> > whether the page contents are messed up. Perhaps this could be worked
> > around if you tried hard enough, but I don't see what we get out of
> > it.
> 
> Is that the how block-level encryption feature from EDB Advanced Server does it?

Uh, EDB Advanced Server doesn't have a block-level encryption feature.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  Indecision is a decision.  Inaction is an action.  Mark Batterson