I have several PostgreSQL DBs in different geographical locations (local sites).
Each local site DB have the same schema, but unique data. For example, Take a table with columns: Site_ID, Department_ID, Department_Name. Site_ID is unique for each site.
I want to collect all the data from the local site DBs into a centralised DB (PostgreSQL again) which acts as a data warehouse.
The corresponding example table on the centralised DB will have the same columns as above. All local site data will go into this table. Each site data designated by the Site_ID, of course.
Question: How to achieve this with PostgreSQL replication methods (streaming/multi-master UDR/BDR/etc.) I see this can be done with SQLServer using Transactional Replication. What is the best way to achieve this functionality with PostgreSQL?
Restriction: The local sites can make only outgoing network connections (i.e. no inbound connections due to firewall restrictions)