Re: [DESIGN] Incremental checksums

On Wed, Jul 15, 2015 at 9:13 PM, David Christensen <david(at)endpoint(dot)com>
wrote:
>
>
> > On Jul 15, 2015, at 3:18 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
wrote:
> >
> > > - pg_disable_checksums(void) => turn checksums off for a cluster.
Sets the state to "disabled", which means bg_worker will not do anything.
> > >
> > > - pg_request_checksum_cycle(void) => if checksums are "enabled",
increment the data_checksum_cycle counter and set the state to "enabling".
> > >
> >
> > If the cluster is already enabled for checksums, then what is
> > the need for any other action?
>
> You are assuming this is a one-way action.
>

No, I was confused by the state (enabling) this function will set.

> Requesting an explicit checksum cycle would be desirable in the case
where you want to proactively verify there is no cluster corruption to be
found.
>

Sure, but I think that is different from setting the state to enabling.
In your proposal above, in enabling state cluster needs to write
checksums, where for such a feature you only need read validation.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com