This is not to say Redis is better or MongoDB is better, it's just a different point of view Sure. I didn't mean to imply any criticism, or imply that you were

This is not to say Redis is better or MongoDB is better, it's just a different point of view Sure. I didn't mean to imply any criticism, or imply that you were criticizing. I, personally, haven't figured out when/where to use a document database like Mongo or Couch, but I figure they must be a good fit for someone's use case or people wouldn't be making them. The thing that I have trouble with is that in every presentation or discussion I've seen of these alternative databases the people presenting them never seem to have an understanding of what a relational database is. And because the language in these presentations is always so obfuscated (to me) I'm never able to get a clear idea of what exactly they do and where they stand in relation to a relational DBMS (by which I mean the platonic ideal of a relational DBMS, not SQL). Redis is interesting to me because it's unlike the others. And because of the way it's unlike the others. It has data structures with operations. In other words it's a DBMS, or "structure server" in your terminology. At its core a relational DBMS is just a "structure server" with one kind of data structure, called a relation, and operations on that structure. And that's all it is really. Others probably disagree but I think even a query language is optional. The query language is just the UI. SQL confuses everything. A SQL DBMS is a relational DBMS (almost) plus a boatload of additional functionality. I see your point about how Mongo is like SQL because it has named values and queries, but it doesn't have relations or relational operators. In summary: Mongo may have some SQL like features, but they aren't relational features. The set features of Redis on the other hand are getting close to the building blocks of the core of an actual relational DBMS.