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