PostgreSQL中的跨数据库参考

Question

I have 4 database db1,db2,db3 and db4, i need to take row count of first 3 table into last on (db4). I have created dblink extension, foreign wrapper and server using below code on db4.

  CREATE EXTENSION dblink;

  CREATE FOREIGN DATA WRAPPER samplewrapper VALIDATOR postgresql_fdw_validator;
  CREATE SERVER demoserver FOREIGN DATA WRAPPER samplewrapper OPTIONS (hostaddr '127.0.0.1', dbname 'db1');

Now i can connect to db1 from db4. But i don't know how to add rest of the db's (db2 and db3) to demoserver . How can i do that??

Answer 1

Remove the dblink extension, you don't need it.

You will have to create three foreign servers to connect to three other databases.