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

Rows and keys


Now we discuss the row and key formats. The naive approach would be to store rows in a MySQL format—what is passed to the write_row() function is written to disk. Thus retrieval would be easy too. Unfortunately, this does not work. For example, this format has all CHAR and VARCHAR fields space padded to their full length. Storing them that way would waste a lot of space. But the main reason why this simple approach is fundamentally flawed is the BLOB type. In memory, all BLOB (and TEXT) fields are kept outside of the row buffer; the row buffer only keeps a pointer to the actual BLOB field content. This is why we use a special packed row format, which makes our code only slightly more complex, as MySQL conveniently provides a Field::pack() method that will do all of the packing job. First, we need a buffer for a packed row. A growing String object (briefly discussed in the previous chapter) would be very handy here. As we do not need more than one row buffer per table, we...