| From: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
|---|---|
| To: | Leonardo Francalanci <m_lists(at)yahoo(dot)it> |
| Cc: | Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Page Checksums |
| Date: | 2011-12-21 22:32:13 |
| Message-ID: | 20111221223212.GB18049@svana.org |
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| Lists: | pgsql-hackers |
On Wed, Dec 21, 2011 at 09:32:28AM +0100, Leonardo Francalanci wrote:
> I can't help in this discussion, but I have a question:
> how different would this feature be from filesystem-level CRC, such
> as the one available in ZFS and btrfs?
Hmm, filesystems are not magical. If they implement this then they will
have the same issues with torn pages as Postgres would. Which I
imagine they solve by doing a transactional update by writing the new
page to a new location, with checksum and updating a pointer. They
can't even put the checksum on the same page, like we could. How that
interacts with seqscans I have no idea.
Certainly I think we could look to them for implementation ideas, but I
don't imagine they've got something that can't be specialised for
better performence.
Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> He who writes carelessly confesses thereby at the very outset that he does
> not attach much importance to his own thoughts.
-- Arthur Schopenhauer
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