Using foreign data wrappers and the postgres_fdw extension

This section will provide a brief introduction to what foreign data wrappers are. Foreign data wrappers allow us to access data that is hosted on an external database as if it was kept on a normal local table. We can connect PostgreSQL to various data sources, we can connect PostgreSQL to another PostgreSQL server, or we can connect PostgreSQL to another data source that can be relational or non-relational. Once the foreign data wrapper is connected, PostgreSQL is able to read the remote table as if it were local. There are foreign data wrappers for well-known databases such as Oracle and MySQL, and there are foreign data wrappers for lesser-known systems. A complete list of foreign data wrappers available for PostgreSQL is available at https://wiki.postgresql.org/wiki/Foreign_data_wrappers.

In this section, we will consider an example using the postgresql_fdw foreign data wrapper, which is used to connect a PostgreSQL server...