Book Image

MySQL 5.1 Plugin Development

Book Image

MySQL 5.1 Plugin Development

Overview of this book

MySQL has introduced a Plugin API with its latest version – a robust, powerful, and easy way of extending the server functionality with loadable modules on the fly. But until now anyone wishing to develop a plugin would almost certainly need to dig into the MySQL source code and search the Web for missing bits of the information.This is the first book on the MySQL Plugin API. Written together with one of the Plugin API primary architects, it contains all the details you need to build a plugin. It shows what a plugin should contain and how to compile, install, and package it. Every chapter illustrates the material with thoroughly explained source code examples.Starting from the basic features, common to all plugin types, and the structure of the plugin framework, this book will guide you through the different plugin types, from simple examples to advanced ones. Server monitoring, full-text search in JPEG comments, typo-tolerant searches, getting the list of all user variables, system usage statistics, or a complete storage engine with indexes – these and other plugins are developed in different chapters of this book, demonstrating the power and versatility of the MySQL Plugin API and explaining the intricate details of MySQL Plugin programming.
Table of Contents (16 chapters)
MySQL 5.1 Plugin Development
Credits
About the Authors
About the Reviewer
Preface

A simple static text output UDF


Returning text in a MySQL UDF can be slightly more complex than dealing with numbers. MySQL gives us a memory buffer to use when returning a string but it is only 766 bytes long. This is fine for some tasks, but not big enough to hold a long string or a blob, so what we do is allocate our own buffer for this purpose. Either way, we need to tell MySQL how long the resulting string is.

The next piece of example code has two UDFs inside it, the first showing how to use the memory buffer that MySQL has given us and the second allocating its own memory. Both are simple UDFs which will just return the MySQL version number that UDF was compiled against:

#include <stdlib.h>
#include <string.h>
#include <mysql.h>
my_bool udf_textexample_init(UDF_INIT *initid,
UDF_ARGS *args, char *message)
{
initid->const_item = 1;
return 0;
}

As with previous examples we create the initialization function. We set initid->const_item to 1 here because the return...