Is there a way in PostgreSQL 12 to restrict user to creating a database with a specific database name?
For example, userA can only create a database with a name called mydb. Any other names would generate an error.
If that is not possible, will it be possible then to limit userA to creating only one database? Granting the createdb privilege would allow the user to create any number of databases which I want to avoid.
No. Though you could prevent them from being able to connect to unexpected databases via the pg_hba.conf file.
Why does userA need create database privileges?
You could just have them log into an admin database and run a function that creates the database for them using function owner privileges then you can add whatever special logic you want to that function.
