Re: Page Checksums - Mailing list pgsql-hackers

From Stephen Frost
Subject Re: Page Checksums
Date
Msg-id 20111219141409.GA24234@tamriel.snowman.net
Whole thread Raw
In response to Re: Page Checksums  (Aidan Van Dyk <aidan@highrise.ca>)
Responses Re: Page Checksums  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
* Aidan Van Dyk (aidan@highrise.ca) wrote:
> But the scary part is you don't know how long *ago* the crash was.
> Because a hint-bit-only change w/ a torn-page is a "non event" in
> PostgreSQL *DESIGN*, on crash recovery, it doesn't do anything to try
> and "scrub" every page in the database.

Fair enough, but, could we distinguish these two cases?  In other words,
would it be possible to detect if a page was torn due to a 'traditional'
crash and not complain in that case, but complain if there's a CRC
failure and it *doesn't* look like a torn page?

Perhaps that's a stretch, but if we can figure out that a page is torn
already, then perhaps it's not so far fetched..
Thanks,
    Stephen    (who is no expert on WAL/torn pages/etc)

pgsql-hackers by date:

Previous
From: Greg Smith
Date:
Subject: Re: archive_keepalive_command
Next
From: Stephen Frost
Date:
Subject: Re: Page Checksums