On Tue, Dec 20, 2011 at 12:12 PM, Christopher Browne <cbbrowne@gmail.com> wrote:
> This seems to be a frequent problem with this whole "doing CRCs on pages" thing.
>
> It's not evident which problems will be "real" ones.
That depends on the implementation. If we have a flaky, broken
implementation such as the one proposed, then, yes, it will be
unclear. But if we properly guard against a torn page invalidating
the CRC, then it won't be unclear at all: any CRC mismatch means
something bad happened.
Of course, that may be fairly expensive in terms of performance. But
the only way I can see to get around that problem is to rewrite our
heap AM or our MVCC implementation in some fashion that gets rid of
hint bits.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company