Monday, May 9, 2011

My Beef with Databases (Part 3)

This is the second in a series of blog posts about my beef with relational databases today, and some musings on how we could make databases better.

I have a bone to pick with the databases of today. It has developed because of the frustrations I've had in writing, deploying, and interacting with databases over the years. In fact, I have three specific issues I want to talk about, and perhaps, come up with a few ideas to make databases great.

Last time, I described my issues with the differences between the data definition between my application and database. So let's talk about my third biggest beef with databases as they exist today.

SQL is a human language used as a communication protocol

Before we go any further, let's make sure we're talking about the same thing. I am NOT talking about relationship databases, I'm fond of those. I am talking about the actual SQL language. You know, "select * from table;". And even then, I don't have a problem with the language itself. It was designed to be human readable first and it just happened to become something of a data exchange language.

I do, however, very much have an issue using it as a communication protocol between two computers. It's clearly not designed for that since it's structure is more linguistic than data structure. For example, you can't leave extra comma's after lists, or leaving an AND at the end of the where clause is invalid, or even change the order of the clauses, which by itself would simplify a lot of code. Just for starters, why isn't "SELECT user_id, username, password, WHERE username='atrodo' AND password LIKE '12345' AND FROM user;' acceptable? It is unambiguous and is far easier for programs to generate.

And that's the root of the problem. We're using programs to generate text that was meant to be written by humans in order to talk to another computer. It's not forgiving, it's not loosely defined, and it's not a data structure.  It's difficult to produce and difficult to parse, and most importantly, is as much of an API as cobol is.

Put another way, are we using Cobol text to create web APIs? Do we exchange ssl keys using C? Are http request headers a perl program?

Less and less SQL inside an application is being hand written. More and more SQL is being generated by ORMs or SQL abstraction layers. And these tools are rarely simple. Quite the opposite actually, they are normally much more complex than they really need to be. And in my experience these SQL generators are used to generate the SQL that works instead of really expressing what data is really wanted.

So then the question I ask myself is, if not SQL, then what? Is XML or JSON really a better option? Absolutely. Both were designed as mappings to real application data structures. In the case of JSON, it is a data structure. They are meant to be a data exchange format first and happen to be somewhat human readable.

Why do we continue to use SQL as a database API?

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