Re: [HACKERS] Online enabling of page level checksums

On 1/22/17 5:13 AM, Magnus Hagander wrote:
> If the system is interrupted before the background worker is done, it
> starts over from the beginning. Previously touched blocks will be read
> and verified, but not written (because their checksum is already
> correct). This will take time, but not re-generate the WAL.

Another option would be to store a watermark of the largest block ID 
that had been verified for each relation/fork. That would be used to 
determine if checksums could be trusted, and more usefully would allow 
you to start where you left off if the verification process got interrupted.

> I think the actual functions and background worker could go in an
> extension that's installed and loaded only by those who need it. But the
> core functionality of being able to have "checksum in progress" would
> have to be in the core codebase.

If it was in contrib I think that'd be fine.
-- 
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
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