Chapter 6: Extending MySQL

Overview

One of the great advantages of MySQL is that it's always been relatively easy to extend MySQL. When early versions of MySQL were accused of being lacking in features, the comeback was always, "Write your own." MySQL has made it easy to do that for anyone competent in C or C++.

You can add functions to MySQL in two ways. Create a user-defined function (UDF) or add a native (built-in) function. You can add UDFs to source and binary distributions, adding or dropping them at any time, but you can add built-in functions only to a source distribution (you modify the source code and compile your additions). This chapter only discusses UDFs. (This chapter uses the term UDF to describe the related set of C/C++ functions that correspond to a single MySQL function. The term function describes a single C/C++ function.)

Featured in this chapter:

• Standard user-defined functions

• Aggregate user-defined functions

• UDF functions and parameters