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
About the Authors
About the Reviewer

Searching in the index

index_read() is, perhaps, the most complex function in our engine. Not because it is difficult to look up a key in the B+tree, but because there are too many "search modes" in MySQL. But let's get started:

int ha_tocab::index_read(uchar *buf, const uchar *key,
uint key_len, enum ha_rkey_function find_flag)

Just like rnd_next(), from the previous chapter this method takes a pointer to a row buffer as an argument. The row that we will find should be written there. Not surprisingly, two other arguments of this method are key and key length—it is what we will need to search for. But the last argument—what is it? It is this very "search mode" that makes our lives complicated. It can take one of the following values:




In this mode, index_read() should find a first row with the key exactly matching the key argument. If no such row exists, it should return HA_ERR_KEY_NOT_FOUND.


In this mode, index_read...