How to execute cross-database queries in PostgreSQL?

To perform cross-database queries in PostgreSQL, you can reference tables from other databases using fully qualified table names. For example, if you want to query a table named table1 in a database called db1, you can use the following syntax:

SELECT * FROM db1.table1;

In this example, db1 is the name of the database to be queried, and table1 is the name of the table to be queried. You can use fully qualified table names in the query to reference tables in other databases, allowing you to perform cross-database queries.