Book Image

Amazon SimpleDB Developer Guide

Book Image

Amazon SimpleDB Developer Guide

Overview of this book

SimpleDB is a highly scalable, simple-to-use, and inexpensive database in the cloud from Amazon Web Services. But in order to use SimpleDB, you really have to change your mindset. This isn't a traditional relational database; in fact it's not relational at all. For developers who have experience working with relational databases, this may lead to misconceptions as to how SimpleDB works.This practical book aims to address your preconceptions on how SimpleDB will work for you. You will be quickly led through the differences between relational databases and SimpleDB, and the implications of using SimpleDB. Throughout this book, there is an emphasis on demonstrating key concepts with practical examples for Java, PHP, and Python developers.You will be introduced to this massively scalable schema-less key-value data store: what it is, how it works, and why it is such a game-changer. You will then explore the basic functionality offered by SimpleDB including querying, code samples, and a lot more. This book will help you deploy services outside the Amazon cloud and access them from any web host.You will see how SimpleDB gives you the freedom to focus on application development. As you work through this book you will be able to optimize the performance of your applications using parallel operations, caching with memcache, asynchronous operations, and more.
Table of Contents (16 chapters)
Amazon SimpleDB Developer Guide
Credits
Foreword
About the Authors
About the Reviewers
Preface

Querying for multi-valued attributes


Retrieve all songs with a rating of 4 stars or ****:

SELECT * FROM songs WHERE Rating = '****' OR Rating = '4 stars'

To retrieve all songs with a rating of '4 stars' and '****' use:

SELECT * FROM songs WHERE Rating = '****' INTERSECTION Rating = '4 stars'

While it may seem logical to use AND, it is not syntactically acceptable to SimpleDB.

getAttribute

SELECT is the most common technique to retrieve items from SimpleDB, but one special case is retrieving one item using the item name. This can be done with a SELECT query, but getAttributes uses about 41% of the box usage of the SELECT query.

getAttributes in Java

In this example, we will retrieve the attributes for an item from SimpleDB. Typica provides a method called getItemsAttributes(), which uses getAttributes under the covers.

SimpleDB sdb = new SimpleDB(awsAccessId, awsSecretKey, true);
try {
Domain domain = sdb.getDomain("songs");
List<String> itemsToGet = new ArrayList<String>();
itemsToGet...