In theory, there is no domain (or finite set of domains) that cannot be accurately modeled using tuples of things and their relations.
Practically speaking, the scope of a given database/schema is generally restricted to one business or problem area, but even this doesn't matter as long as the types aren't aliasing inappropriately. You could put a web retailer and an insurance company in the same schema and it would totally work if you are careful with naming things.
Putting everything into exactly one database is a superpower. The #1 reason I push for this is to avoid the need to conduct distributed transactions across multiple datastores. If all business happens in one transactional system, your semantics are dramatically simplified.
In theory, there is no domain (or finite set of domains) that cannot be accurately modeled using tuples of things and their relations.
Practically speaking, the scope of a given database/schema is generally restricted to one business or problem area, but even this doesn't matter as long as the types aren't aliasing inappropriately. You could put a web retailer and an insurance company in the same schema and it would totally work if you are careful with naming things.
Putting everything into exactly one database is a superpower. The #1 reason I push for this is to avoid the need to conduct distributed transactions across multiple datastores. If all business happens in one transactional system, your semantics are dramatically simplified.