Efficiency takes work.

I came across the following paper recently. Titled in part One Size Fits All?, it shows how text processing benefits enormously from the use of specialized databases. They compare the performance of standard relational databases (RBMS) with the performance of systems designed to solve specific problems. They convincingly demonstrate that specialized systems can easily obtain two orders of magnitute better performance than RDBMS.

The reasons have to do with careful design, and choosing the right tool for the job. RDBMS are designed to do a number of things very well, but they're not spectacular at solving any one problem. If you want to quickly prototype a system, RDBMS are a good choice. But if you want a fast system, it's best to pay close attention to the design of the system.

The same design methods apply in the RADIUS space, too. It's easy to set up a RADIUS server that uses an SQL database to store authorization rules and accounting data. It's much more difficult to build a system that has the same functionality, but scales to 100 times the load of a “simple” design. But as my previous post showed, FreeRADIUS has (of course) no problem being part of such a system.