| From: | Antonin Houska <ah(at)cybertec(dot)at> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Bruce Momjian <bruce(at)momjian(dot)us>, Sehrope Sarkuni <sehrope(at)jackdb(dot)com>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Joe Conway <mail(at)joeconway(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, "Moon, Insung" <Moon_Insung_i3(at)lab(dot)ntt(dot)co(dot)jp>, Ibrar Ahmed <ibrar(dot)ahmad(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [Proposal] Table-level Transparent Data Encryption (TDE) and Key Management Service (KMS) |
| Date: | 2019-11-02 12:24:37 |
| Message-ID: | 4100.1572697477@antos |
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| Lists: | pgsql-hackers |
Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Mon, Aug 5, 2019 at 8:44 PM Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> > Right. The 8k page LSN changes each time the page is modified, and the
> > is part of the page nonce.
>
> What about hint bit changes?
>
> I think even with wal_log_hints=on, it's not the case that *every*
> change to hint bits results in an LSN change.
Change to hint bits does not result in LSN change in the case I described here
https://www.postgresql.org/message-id/28452.1572443058%40antos
but I consider this a bug (BTW, I discovered this problem when thinking about
the use of LSN as encryption IV). Do you mean any other case? If LSN does not
get changed, then the related full-page image WAL record is not guaranteed to
be on disk during crash recovery. Thus if page checksum is invalid due to
torn-page write, there's now WAL record to fix the page.
--
Antonin Houska
Web: https://www.cybertec-postgresql.com
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