Distributed Database Systems are always being the potential Research area in Computer Science. The effective way of managing the growing volume of Data in Distributed Database Systems is a Herculean task. The recent technological developments in Peer-to-Peer (P2P) systems gained a global momentum towards network implementation. This is the main reason to incorporate Database functionality with P2P systems to design Peer-to-Peer Distributed Database Systems (P2PDDBS). This phenomenon is better than a single and conventional Client/Server databases because the accessibility and availability of Data is higher in P2PDDBS. This book is mainly focused on proposing optimized Data Allocation strategies using Ant Colony Optimization method and Hungarian Assignment Algorithm in order to achieve higher degree of Accessibility and Availability of data in P2PDDBS, which will lead to better and quicker query processing. This book will be very helpful to the Research community, working with Distributed Database Systems.