| From: | Greg Smith <greg(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Craig Ringer <craig(at)2ndQuadrant(dot)com> |
| Cc: | Markus Wanner <markus(at)bluegap(dot)ch>, Jeff Davis <pgsql(at)j-davis(dot)com>, Jesper Krogh <jesper(at)krogh(dot)cc>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Enabling Checksums |
| Date: | 2012-11-12 23:02:42 |
| Message-ID: | 50A18012.2080402@2ndQuadrant.com |
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| Lists: | pgsql-hackers |
On 11/12/12 4:44 AM, Craig Ringer wrote:
> Is it absurd to suggest using another bitmap, like the FSM or visibility
> map, to store information on page checksumming while checksumming is
> enabled but incomplete?
I spent some time thinking about that last week. One problem with it is
that the bitmap structure itself has the same issues as every other
write here--how do we know it's going to disk accurately? The "put
'checksum on' bits on the page" idea and "put checksum on bits in a map"
have the same fundamental issue. Things might get out of sync in the
same way, you've just moved the potentially suspicious write to a new place.
--
Greg Smith 2ndQuadrant US greg(at)2ndQuadrant(dot)com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com
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