I have been using replication slot since its birth in PostgreSQL 9.4 version. This feature is very helpful in terms of keeping the WAL files on master server to make sure that its replica servers are in good state and (a)sync with it. But, something horrible will happen if you left them inactive.
In one of our database clusters, the design was simply like this:
Available in English and Indonesian versions.
Up until this moment, PostgreSQL version 9.x, the only way to have limited replication, as in tables and its data and not the whole database cluster, is to use dump and restore option or the trigger. And if you wanto to use the trigger option, the only tools with this capability are Bucardo and Skytool’s Londiste with their own good and bad side. You can easily set trigger-based replication up and the replicated data you have is mostly nearly realtime unless you forgot to run the daemon. On the other hand, dump and restore options doesn’t give you the ability to have near realtime replication but the limitation gives you more power over the trigger-based one. (Depending on how you look at it)