The cost-based optimizer of IBM DB2 for z/OS has continually evolved since its initial inception. Support has included new optimization algorithms, join methods, complex relational data structures, such as star schemas. DB2 for z/OS V8 has provided access path visualization and a Statistics Advisor function through a new Visual Explain. DB2 9 for z/OS starts addressing the challenge of reducing cost of ownership by extending query optimization through expert-based query and workload analysis, server enhancements, and an Index Advisory function. These functions are delivered with two tools: DB2 Optimization Service Center and DB2 Optimization Expert. This book helps you understand the installation, customization, and usage aspects of the tools. You are guided through scenarios of gradually increasing complexity where the functions of the tools are exploited for query optimization.

Conducting business via the Web and remaining open for business 24 hours a day, seven days a week is now commonplace. Customers come in with unexpected workloads through the Web and operate in a self-service fashion with mostly context-sensitive metadata to guide them. The strong requirement is availability. However, even with new Web applications, most of the core business systems considerations still apply, and performance is critical. Technology has been accelerating for mainframe systems. They had become adept at providing business resiliency accommodating strategic software that has been around for the last several decades such as IMS™ , DB2® , and CICS® , and they have also become a host for developing and running Web applications built in Java™ accommodating the latest business requirements. Businesses need to leverage, extend and integrate the strategic assets which represent multi-year investments to support leading edge technology. DB2 for z/OS® has come a long way and provides facilities to exploit the latest hardware and software technologies, accommodating a majority of user requirements. However, special considerations are required to build high performance applications. If you want to achieve high performance or high availability, you must use the design, programming, and operational techniques applicable to DB2. Please note that the additional material referenced in the text is not available from IBM.

In many organizations, relational databases are the backbone for data storage and retrieval. Over the last couple of years, XML has become the de facto standard to exchange information between organizations, as well as between departments or applications within the same organization. Since data tends to live in databases, it needs to be converted from a relational format into an XML format when involved in those data exchanges, as well as converted (back) from XML into a relational format for storage, or for handling by other applications. How can we achieve this? This IBM Redbooks publication describes how to design the mapping between XML and relational data, and vice versa, to enable a flexible exchange of information. IBM provides a number of products to help you bridge the gap between XML and its relational database, DB2. The DB2 engine itself provides support to generate XML fragments from relational data through the use of SQL/XML built-in functions. DB2 also provides the DB2 XML Extender. It allows you to perform XML composition, like SQL/XML, but also provides functionality to decompose XML documents and store XML documents intact inside the database. XML Extender also provides a set of transformation and validation functions. Another option to work with XML is to use the XML wrapper, a part of the set of non-relational wrappers of DB2 Information Integrator. This book also looks at the IBM tools available to assist you when dealing with XML, specifically WebSphere Application Developer and DB2 Control Center. Please note that the additional material referenced in the text is not available from IBM.