At Braviant Holdings we consider foreign data wrappers to be the best thing even introduced in PostgreSQL. We use them virtually everywhere, both for our apps which interact with OLTP databases and for the ETL for our Data Warehouse.
One of the best things about using the FDW is that they allow you to map objects of various types. You can map tables, views, other foreign tables, you can use indexes remotely/ You can even map a query!
But what about mapping functions? Strictly speaking, there is no way, but as usual, when there is a will, there is a way.
In this talk we will show how ability to call the functions remotely assisted our transition from the legacy system to the newly designed service-based framework and allowed to maintain the data accuracy and consistency.