postgres_fdw: access data stored in external PostgreSQL servers

[amotl]

About

The postgres_fdw module provides a foreign-data wrapper, which can be used to access data stored in external PostgreSQL servers. In this spirit, it can also be used to talk to CrateDB.

Details

@hlcianfagna had a nice conversation with @ishurmer over at CrateDB/postgres_fdw/LIMIT parameter. Thanks.

Request for re-evaluation

Because there was an issue, which now has been fixed by crate/crate#13835, we may want to try again if the situation is better now. As a bonus, we may have a short code snippet hooked into https://github.com/crate/cratedb-examples, in order to constantly validate connectivity, see CrateDB Ecosystem Build Status.

Request for documentation

If everything works well, let's demonstrate corresponding functionality better on behalf of a relevant blog post, which outlines a minimal but holistic scenario using this tech.

/cc @wierdvanderhaar, @matkuliak