We have slony working for basic backup from an "active" to a "standby" in a 2-node cluster, and it's great. I've been trying to leverage our slony infrastructure to support another kind of replication we need to do, but I'm beginning to think it's not a fit.

Each cluster we have also needs to replicate some data from a central repository. I posted an earlier question on this because I need the active to forward some data to its standby, but the active also masters some data. Christopher Browne suggested defining separate slony clusters, which should work because there are distinct replication sets.

After I spec'd out this topology I realized that I had been more or less in denial about the fact that our deployment over the next year or so will probably dictate up to 70 of these clusters needing to replicate from the central repository (we want to replicate out to these clusters as a caching/locality-of-reference thing).

This obviously means that the listener connections will be out of control, and, I fear, pretty much kills the idea. BUT, I'm wondering if there is any way around having all of these listeners?

For the set mastered on the central repository, NONE of the clusters will ever take over as master of that set - the central repository is itself a cluster. So in our environment, I'm not sure that every cluster (the active node) needs a listener to every other active node. As I understand it, these inter-subscriber connections are to make sure that SYNCs are up-to-date across the network, but if none of these can ever become master (dictated at the application level), can I get away without having the listeners for them?

I would really like to be able to use slony for this part of our infrastructure, because it does exactly what we need, but I know we won't be able to support the number of database processes on each box that the default topology would require.

Any comments/suggestions appreciated. Thanks.

- DAP
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David Parker    Tazz Networks    (401) 709-5130
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