| From: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
|---|---|
| To: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov> |
| Cc: | simon(at)2ndQuadrant(dot)com, stark(at)mit(dot)edu, aidan(at)highrise(dot)ca, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: 16-bit page checksums for 9.2 |
| Date: | 2011-12-27 20:05:11 |
| Message-ID: | 4EFA24F7.6090007@enterprisedb.com |
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| Thread: | |
| Lists: | pgsql-hackers |
On 25.12.2011 15:01, Kevin Grittner wrote:
> I don't believe that. Double-writing is a technique to avoid torn
> pages, but it requires a checksum to work. This chicken-and-egg
> problem requires the checksum to be implemented first.
I don't think double-writes require checksums on the data pages
themselves, just on the copies in the double-write buffers. In the
double-write buffer, you'll need some extra information per-page anyway,
like a relfilenode and block number that indicates which page it is in
the buffer.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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