The Slony-I documentation states the following:


"This points to it being a bad idea to have the large communications 
network resulting from the number of nodes being large. Up to a half dozen 
nodes seems pretty reasonable; every time the number of nodes doubles, this 
can be expected to quadruple communications overheads."

Consider a setup with dozens of very small nodes which aren't heavliy 
frequented. Neither of these nodes is considered to be a forwarder and 
stores only information which aren't updated frequently (so we consider a 
small database between 20 - 30 MB).  The Lagtime can be minutes (we don't 
care wether 5 or 15 minutes). The network is stable.

I wonder wether the number of nodes can be significantly larger than the 
half dozens the documentation mentions, especially if you don't need to use 
Failover, MOVE SET and you are able to use high SYNC timeouts values. For 
example, this can be configuration clusters of a large network where 
configuration changes needs to be propagated through a large number of 
nodes.

A customer is planning such a setup and they consider Slony-I exactly for 
this purpose since they are impressed about its reliability. However, 
because communications cost is quadratic, there can be significant network 
traffic.

Opinions? Experiences?

-- 
  Thanks

                    Bernd