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How do NoSQL / graph databases support foreign keys or joins? Do they have the concept of referential integrity?

The point of a DBMS is to do this for you, via the SQL table declarations. AIUI, NoSQL / graph databases cannot do this at the system level and needs to be done by an application-level framework.

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Some (many?) SQL shops turn off some of the referential integrity checks on their production transactional workloads anyway, making that an application responsibility.

I have not heard of any place doing this for many years.

Thank you, I agree!

I don't think you can enforce a constraint on which nodes are supposed to have which edges, etc.

I'm curious: is there a reason why you're putting NoSQL and graph databases into the same bucket, other than them both having the aforementioned limitation?

There are many different kinds of NoSQL db's. Graph db's are just one type of NoSQL db.

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