I would like to share feedback from a developer perspective regarding cross-database querying in PostgreSQL.
One feature that many developers appreciate in MySQL is the ability to directly query and join tables across multiple databases within the same server instance. This approach becomes very useful in real-world situations where applications need to access shared or distributed data quickly and efficiently.
What MySQL calls databases PostgreSQL calls schemas, and PostgreSQL certainly has the ability to query and join tables across schemas.
What MySQL might call an instance (a collection of MySQL databases) PostgreSQL calls a database (a collection of PostgreSQL schemas). A single PostgreSQL instance has the ability to host multiple databases (albeit sharing a single set of roles and role relationships). Can MySQL query and join across multiple instances?
mysql treats SCHEMA and DATABASE the same. So the features are at parity from an isolation standpoint. (This is also why you won't get this feature since most of the benefits from cross database querying are already present).
Besides. postgres schemas are better in pretty much every way, mainly due to the games you can play with search_path and plan invalidation, especially in p/pgsql.
