Actually we have to improve what our replicator is doing: it's only replicating the single user's database. The improvement should that we can put it on the "server" (in some cases there are groups of users sharing a dedicated server) and, given a configuration of what and how to replicate, it should replicate more than one DB a time.
That's a layer on top as far as pglogical is concerned. It's only interested in a single database at a time.
The same is true of BDR.
A tool that automatically configures newly found databases to be replicated should be pretty trivial to write, though.
We were beginning to "translate" (and then improve) this program in c#, when I bumped into articles pointing to BDR, and I started taking a look. But it seems that is good to replicahe whole servers, and still hasn't the granularity we need.
Huh?
BDR is configured database-by-database. The only exception is with bdr_init_copy, for initial setup using binary base backups; in that case all databases are copied.
It sounds like you actually *want* to replicate all databases at once. Presumably the reason you're not just using physical streaming replication for that is that different hosts have a different set of writeable databases? E.g.
[Node A] [Node B]
[DB-1] -> [DB-1]
[DB-2] -> [DB-2]
[DB-3] <- [DB-3]
[DB-4] <- [DB-4]
so each DB is written from only one node at a time, but both nodes have writeable DBs. Right?