Re: storing an explicit nonce - Mailing list pgsql-hackers

From Stephen Frost
Subject Re: storing an explicit nonce
Date
Msg-id 20210525235929.GT20766@tamriel.snowman.net
Whole thread Raw
In response to Re: storing an explicit nonce  (Andres Freund <andres@anarazel.de>)
List pgsql-hackers
Greetings,

* Andres Freund (andres@anarazel.de) wrote:
> On 2021-05-25 17:22:43 -0400, Stephen Frost wrote:
> > Err, to be clear, I was saying that we could exclude the hint bits
> > *entirely* from what's being encrypted and I don't think that would be a
> > huge issue.
>
> It's a *huge* issue. For one, the computational effort of doing so would
> be a problem. But there's a more fundamental issue: We don't even know
> the type of the page at the time we write data out! We can't do a lookup
> of pg_class in the checkpointer to see whether the page is a heap page
> where we need to mask out hint bits.

Yeah, I hadn't been contemplating the challenge in figuring out if the
changes were hint bit changes or if it was some other page- merely
reflecting on the question of if hint bits, themselves, could possibly
be excluded.

Thanks,

Stephen

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