NoSQL / RDBMS hybrid with referential integrity (delete cascade)?

Question

Is there a database out there that gives you the benefit of referential integrity and being able to use a SQL type language for querying, but also lets entities be loosely defin

Answer 1

Most NoSQL databases are built to scale very well. This is done at the cost of consistency, of which referential integrity is part of. So most NoSQL don't support any type of relational constraints.

There's one type of NoSQL database that does support relations. In fact, it's designed especially for relations: the graph database. Graph databases store nodes and explicit relations (edges) between these nodes. Both nodes and edges can contain data in the form of key/value pairs, without being tied to a predefined schema.

Graph databases are optimized for relational queries and nifty graph operations, such as finding the shortest path between two nodes, or finding all nodes within a given distance from the current node. You wouldn't need this in a role/permission scenario, but if you do, it'll be a lot harder to achieve using an RDBMS.

Another option is to make your entire data layer a hybrid, by using a RDBMS to store the relations and a document database to store the actual data. This would complicate your application slightly, but I don't think it's such a bad solution. You'll be using two different technologies, both dealing with the problems they were designed to deal with.