> Before I embark on replicating to 3 different postmasters or schemas and
> then implementing triggers to aggregate data, I'm wondering if the Slony
> slave can be configured to read from the 3 locations 1, 2 and 3 and
> simply aggregate the data received.

It seems reasonable to replicate the data into 3 different schemas (one
for each branch) then use a number of views with UNIONS in 4th schema.

I believe you can subscribe to sets from different sources with a single
client -- though I've not tried it.