Xaprb

Dr. Richard Hipp gave a talk at Southeast Linux Fest today on choosing an open-source database. He thinks that NoSQL is not a very good name for the new databases we’re seeing these days, so he proposed a new name: postmodern databases. Why postmodern?

• The absence of objective truth
• Queries return opinions, not facts

I thought this was the best proposal I’ve heard for an alternative to the NoSQL moniker. And this is not bashing — the absence of objective truth can actually be an enabling quality, not necessarily a drawback. There’s a lot to compliment about the new databases, and calling them NoSQL is really a disservice — like calling a car a horseless carriage.

It seems that a lot of people equate non-SQL databases with non-relational-ness, or malign the word relational. This is pretty much pure ignorance. If you’ve ever uttered a sentence that includes the phrase “…non-relational database…” then I have two suggestions for you.

1. Study relational algebra. At a bare minimum, read the Wikipedia article on relational algebra. There is much more you could do — take a class on the topic, or read C.J. Date’s SQL and Relational Theory (my review). Ask yourself how similar SQL is to the relational algebra. How is relational algebra different from SELECT and GROUP BY? Is relational theory about relationships between data? What part do transactions play in relational algebra? Is MySQL a relational database? What about PostgreSQL, Oracle, or DB2?
2. Now that you understand relational theory more, choose a database that you think is non-relational and write a formal proof that it is not relationally complete. Please do post a link to the proof in the comments.

The truth is, a non-relational database would be of very little use. In layman’s terms, it would mean you have some data that represents true statements, and a piece of software designed to answer questions using those facts, and you can’t answer simple first-order logic questions with the software. How is this an improvement? How is this useful?

As long as the whole world is chasing this meaningless “NoSQL” buzzword, we should recognize that InnoDB is usable as an embedded database without an SQL interface. Hence, it is as much of a NoSQL database as anything else labeled with that term. And I might add, it is fast, reliable, and extremely well-tested in the real world. How many NoSQL databases have protection against partial page writes, for example?

It so happens that you can slap an SQL front-end on it, if you want: MySQL.