Re: Block-level CRC checks

Simon Riggs wrote:
> There is no "creation" of corruption events. This scheme detects
> corruption events that *have* occurred. Now I understand that we
> previously would have recovered seamlessly from such events, but they
> were corruption events nonetheless and I think they need to be reported.
> (For why, see Conclusion #2, below).

No, you're still missing the point. The point is *not* random bit errors
affecting hint bits, but the torn page problem. Today, a torn page is a
completely valid and expected behavior from the OS and storage
subsystem. We handle it with full_page_writes, and by relying on the
fact that it's OK for a hint bit set to get lost. With your scheme, a
torn page would become a corrupt page.

--  Heikki Linnakangas EnterpriseDB   http://www.enterprisedb.com