Writing MySQL functions in C
Andreas Jansson | 15 December 2010
In the previous post Zdenek explained how to use MySQL stored functions to calculate the distance between two points on the lat/lng plane. Here I take his function as a starting point to describe how to implement user defined functions written in C, and import them into MySQL.
User defined functions (UDF) are compiled C functions that you can use as normal functions within MySQL. UDFs have a number of advantages over stored functions written using SQL, the most important being improved performance and the fact that you can use them as aggregate functions (like you can with SUM(), AVG(), etc.).
Writing UDFs is easy. So is compiling and importing UDFs into MySQL. First you need to do a little bit of setting up. This is how you do it (in Ubuntu and Red Hat).
