Putting and Getting Data from a Database
Overview of database structures and and data operations on those structures by Marko A. Rodriguez.
Marko covers primitive, key-value, and document stores, plus graph databases.
There are a number of database structures in addition to those four, although those are certainly popular ones.
I would not put too much stock into claims about one form of technology or another until I saw it in operation with my data.
That software works great with someone else’s data isn’t all that interesting, either for you or your manager.