Understanding DB2: Learning Visually with Examples
April 1, 2008
Understanding DB2: Learning Visually with Examples, 2nd Edition
Authors: Raul F. Chong, Xiaomei Wang, Michael Dang, Dwaine R. Snow
Publisher: IBM Press
Pub Date: December 29, 2007
Print ISBN-10: 0131580183
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Chapter 1: Introduction to DB2
DATABASE 2 (DB2) for Linux, UNIX, and Windows is a data server developed by IBM. Version 9.5, available since October 2007, is the most current version of the product, and the one on which we focus in this book.
In this chapter you will learn about the following:
1.1 Brief History of DB2
Since the 1970s, when IBM Research invented the Relational Model and the Structured Query Language (SQL), IBM has developed a complete family of data servers. Development started on mainframe platforms such as Virtual Machine (VM), Virtual Storage Extended (VSE), and Multiple Virtual Storage (MVS). In 1983, DB2 for MVS Version 1 was born. "DB2" was used to indicate a shift from hierarchical databasessuch as the Information Management System (IMS) popular at the timeto the new relational databases. DB2 development continued on mainframe platforms as well as on distributed platforms. Figure 1.1 shows some of the high-lights of DB2 history.
In 1996, IBM announced DB2 Universal Database (UDB) Version 5 for distributed platforms. With this version, DB2 was able to store all kinds of electronic data, including traditional relational data, as well as audio, video, and text documents. It was the first version optimized for the Web, and it supported a range of distributed platformsfor example, OS/2, Windows, AIX, HP-UX, and Solarisfrom multiple vendors. Moreover, this universal database was able to run on a variety of hardware, from uniprocessor systems and symmetric multiprocessor (SMP) systems to massively parallel processing (MPP) systems and clusters of SMP systems.
Even though the relational model to store data is the most prevalent in the industry today, the hierarchical model never lost its importance. In the past few years, due to the popularity of eXtensible Markup Language (XML), a resurgence in the use of the hierarchical model has taken place. XML, a flexible, self-describing language, relies on the hierarchical model to store data. With the emergence of new Web technologies, the need to store unstructured types of data, and to share and exchange information between businesses, XML proves to be the best language to meet these needs. Today we see an exponential growth of XML documents usage.
IBM recognized early on the importance of XML, and large investments were made to deliver pureXML technology; a technology that provides for better support to store XML documents in DB2. After five years of development, the effort of 750 developers, architects, and engineers paid off with the release of the first hybrid data server in the market: DB2 9. DB2 9, available since July 2006, is a hybrid (also known as multi-structured) data server because it allows for storing relational data, as well as hierarchical data, natively. While other data servers in the market, and previous versions of DB2 could store XML documents, the storage method used was not ideal for performance and flexibility. With DB2 9's pureXML technology, XML documents are stored internally in a parsed hierarchical manner, as a tree; therefore, working with XML documents is greatly enhanced. In 2007, IBM has gone even further in its support for pureXML, with the release of DB2 9.5. DB2 9.5, the latest version of DB2, not only enhances and introduces new features of pureXML, but it also brings improvements in installation, manageability, administration, scalability and performance, workload management and monitoring, regulatory compliance, problem determination, support for application development, and support for business partner applications.
DB2 is available for many platforms including System z (DB2 for z/OS) and System i (DB2 for i5/OS). Unless otherwise noted, when we use the term DB2, we are referring to DB2 version 9.5 running on Linux, UNIX, or Windows.
DB2 is part of the IBM information management (IM) portfolio. Table 1.1 shows the different IM products available.
Table 1.1 Information Management Products