Re: standby registration (was: is sync rep stalled?)

On Oct 4, 2010, at 2:02 PM, Robert Haas wrote:

> On Mon, Oct 4, 2010 at 1:57 PM, Markus Wanner <markus(at)bluegap(dot)ch> wrote:
>> On 10/04/2010 05:20 PM, Robert Haas wrote:
>>> Quorum commit, even with configurable vote weights, can't handle a
>>> requirement that a particular commit be replicated to (A || B) && (C
>>> || D).
>>
>> Good point.
>>
>> Can the proposed standby registration configuration format cover such a
>> requirement?
>
> Well, if you can name the standbys, there's no reason there couldn't
> be a parameter that takes a string that looks pretty much like the
> above. There are, of course, some situations that could be handled
> more elegantly by quorum commit ("any 3 of 5 available standbys") but
> the above is more general and not unreasonably longwinded for
> reasonable numbers of standbys.

Is there any benefit to be had from having standby roles instead of individual names? For instance, you could integrate this into quorum commit to express 3 of 5 "reporting" standbys, 1 "berlin" standby and 1 "tokyo" standby from a group of multiple per data center, or even just utilize role sizes of 1 if you wanted individual standbys to be "named" in this fashion. This role could be provided on connect of the standby is more-or-less tangential to the specific registration issue.

Regards,

David
--
David Christensen
End Point Corporation
david(at)endpoint(dot)com