Using a foreign table in a query
Foreign tables exist as empty shells on the local database, lending merely their structure for query-planning and data-fetching purposes. The foreign data wrapper transforms data requests to something the remote server can understand and presents it in a way PostgreSQL will recognize.
As we're using the postgres_fdw wrapper, the situation is simplified. A PostgreSQL server should have less trouble communicating with another PostgreSQL server than an Oracle server, for instance. Though this means less transformation, there are still limitations to what functionality a foreign table might provide compared to a local table.
In this recipe, we'll use a foreign table in a few scenarios and examine how it performs in each. We'll also explore some of the common caveats involved in foreign table access.
Getting ready
As we will be using the pgbench_accounts foreign table in this recipe, please follow all the previous recipes before proceeding.
