[bind10-dev] initial ideas on the "difference" design

[JINMEI Tatuya / 神明達哉]

At Thu, 13 Oct 2011 19:13:22 +0100,
Stephen Morris <stephen at isc.org> wrote:

> > Cool, but note that we still cannot directly use the versions for 
> > comparison unless we internally convert SOA serials to
> > monotonically increase numbers.
> 
> I suppose there are two cases here:
> 
> 1) For whatever reason, a server capable of IXFR-out is loaded with a
> copy of the zone that has a lower-serial number than the current
> version.
> 
> 2) The rollover of the serial number (something I overlooked).

I meant #2 in this context.  We should consider and react to the case
where the zone and the journal somehow have broken data, but that's
beyond the scope of this initial idea, and for error handling cases it
should be okay to do something special.

> are right that we can't then compare serial numbers for greater/less
> than, but we can do equality checks.  Assuming that we are just
> wanting the differences for version B through to the latest version of
> the zone, we would have something like:
> 
> select * from diffs where
> zone_id = Z and
> id >= (select id from diffs where
>    zone_id = Z and version = B and operation = 0
>    order by id asc limit 1)
> order by id asc

You're right that we can still safely use 'version = B', although your
revised example is getting more complicated, more closer to my
original example in complexity:-)

But again, this level of details don't have to be fixed right now.  We
can start with any workable one and then upgrade it as we see the need
for it.

---
JINMEI, Tatuya