distributed databases

This publication is good for an quick introductory view of server load balancers. Users of load balancing products from certain manufacturers will benefit from the configuration options discussed in the final section of the book. For a more in-depth discussion, I would recommend Kopparapu's text "Load Balancing Servers, Firewalls, and Caches".

I expected a lot more from this book that while admittedly was the first that covered the topic, but did not really explain things in detail. Half of the book is on configurations that you can download from vendor web sites and the real design issues are never really addressed. The author runs a web site on teh topic and also is a known expert so this made the book more dissappointing.
The first O'Reilly book I have ever regretted buying.

This deals mainly the web based load balancing. This is the simplest solution since the sessions only last for ms. It has a good hands on approach to router configuration and network design but lacks hardcore application design that this topic deserves.

There is no discussion on complex systems which require sessions to last for days and how to distribute state between multiple servers. There is also no discussion on locking mechanisms, determining load, primary/backup determination, latency across WANs, distributed objects, DB failover, server synchronization, heartbeat implementations, shifting load for scheduled down time, or dynamic router configuration or alternative scheduling mechanism apart from round robin.

I think the title "Web Server Load Balancing" would be a more appropriate title and if that is what your goal is then this is the book for you.