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

On Mon, 2010-10-04 at 14:25 -0500, David Christensen wrote:

> 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.

There is substantial benefit in that config.

If we want to do relaying and path minimization, as is possible with
Slony, we would want to do

M -> S1 -> S2 where M is in London, S1 and S2 are in Berlin.

so that the master sends data only once to Berlin.

If we send to a group, we can also allow things to continue working if
S1 goes down, since S2 might then know it could connect to M directly.

That's complex and not something for the first release, IMHO.

--
Simon Riggs www.2ndQuadrant.com
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