Horton

Re: better page-level checksums

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Bruce Momjian <bruce@momjian.us>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-06-15T02:29:44Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Rethink method for assigning OIDs to the template0 and postgres DBs.

  2. pg_upgrade: Preserve database OIDs.

  3. pg_upgrade: Preserve relfilenodes and tablespace OIDs.

  4. Fix for new Boolean node

  5. Improve error handling of HMAC computations

  6. Add macro RelationIsPermanent() to report relation permanence

  7. Enhance nbtree index tuple deletion.

On Tue, Jun 14, 2022 at 7:17 PM Robert Haas <robertmhaas@gmail.com> wrote:
> But it seems
> absolutely clear that our goal ought to be to leak as little
> information as possible.

But at what cost?

Basically I think that this is giving up rather a lot. For example,
isn't it possible that we'd have corruption that could be a bug in
either the checksum code, or in recovery?

I'd feel a lot better about it if there was some sense of both the
costs and the benefits.

> > Let's assume for now that we don't leave pd_flags unencrypted, as you
> > have suggested. We're still discussing new approaches to checksumming
> > in the scope of this work, which of course includes many individual
> > cases that don't involve any encryption. Plus even with encryption
> > there are things like defensive assertions that can be added by using
> > a flag bit for this.
>
> True. I don't think we should be too profligate with those bits just
> in case somebody needs a bunch of them for something important in the
> future, but it's probably fine to use up one or two.

Sure, but how many could possibly be needed for this? I can't see it
being more than 2 or 3. Which seems absolutely fine. They *definitely*
have no value if nobody ever uses them for anything.

-- 
Peter Geoghegan