Re: pglogical most basic setup for logical replication

I'll update the docs to mention the extra step on 9.4.

 

It's because internally pglogical relies on pg_dump and pg_restore to set up the initial database state. If it fails partway through a pg_restore there's no sensible way to undo those changes, especially since we have to do it in a number of steps to achieve a partial restore.

A cleaner handling of this really requires the ability to use pg_dump's functionality over a normal protocol connection from SQL, or at least as a library.

The error should probably get a HINT to say that an incomplete restore means the DB may have to be dropped and recreated.

It's all a bit messy, since we support multiple upstreams and support writes directly into the downstream. So you actually can't always just drop the downstream. A really good solution to this needs the ability to compare various objects (type definitions, tables, etc), the ability to extract just a required subset of dependencies from a database and other complexities.