On Sat, Jul 20, 2019 at 07:30:30PM +0200, Tomas Vondra wrote:
> Forbid checksums? I don't see how that could be acceptable. We either have
> to accept the limitations of the current design (having to decrypt
> everything before checking the checksums) or change the design.
Yes, checksums certainly have to work.
> I personally think we should do the latter - not just because of this
> "decrypt-then-verify" issue, but consider how much work we've done to
> allow enabling checksums on-line (it's still not there, but it's likely
> doable in PG13). How are we going to do that with encryption? ISTM we
> should design it so that we can enable encryption on-line too - maybe not
> in v1, but it should be possible. So how are we going to do that? With
> checksums it's (fairly) easy because we can "not verify" the page before
> we know all pages have a checksum, but with encryption that's not
> possible. And if the whole page is encrypted, then what?
Well, I assumed we would start with a command-line offline tool to
add/remove encryption, and I assumed the command-line tool pg_checksums
would use the same code to decrypt the page to add/remove checksums and
rewrite it. I don't think we will ever allow add/remove encryption in
online mode.
Does that help?
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
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