Robert Treat and I had some back and forth emails a few weeks ago about explaining database replication to customers. Replication is totally cool but it is also completely confusing to a lot of people. The basic concepts are not widely understood. Plus PostgreSQL does not help by giving you a wide range of methods, often with poorly documented trade-offs.
Based on our conversation I put together a talk for PG West in Portland called Getting Smart about the New World of PostgreSQL Replication. It explains basic concepts and surveys five replication approaches. Press the title and you can possess the slides yourself.
Robert and I had talked about putting together a joint talk about replication. Consider this a first cut. I'm up for iterating a few times to get a solid tutorial.
Meanwhile at Continuent we should be able to replicate data from Oracle or MySQL into PostgreSQL using Tungsten Replicator within about two weeks or so. I'm waiting for one more check-in to enable writing plug-ins that apply SQL to new databases. Sad to say, reading data out of PostgreSQL is going to take a little longer. Stay tuned...