Dear Laurenz, That means a solid monolith database. We lose many goodies with that. As a real-world example, right now we can import a single database from the production to the development to test and troubleshoot data.
What if we host all databases on the same server and use FDW. What happens in that case? Does it return 100 thousand records and join in the memory? Because in SQL Server, when you perform a cross-database query (not cross-server) the performance is extremely good, proving that it does not return 100 thousand ItemId from Taxonomy.ItemCategories to join with ProductId. Is that the same case with Postgres too, If databases are located on one server? Regards Saeed