Datalink manual

Foreign servers

For URLs of scheme file and a non null server, the server name is taken to be a name of postgres_fdw foreign server. If one is found and the extension dblink is installed then the request is passed on to the foreign server. Datalink extension needs to be installed on the foreign server as well for this to work.

mydb=# create extension postgres_fdw;
CREATE EXTENSION
mydb=# create server mydb foreign data wrapper postgres_fdw;
CREATE SERVER
mydb=# create user mapping for current_role server mydb;
CREATE USER MAPPING
mydb=# select body from datalink.curl_get('file://mydb/etc/issue');
         body        
 --------------------
  Ubuntu 23.10 \n \l


(1 row)

Datalink manual