The goal of database performance tuning is to minimize the response time of your queries. It is also to optimize your server's resources by minimizing network traffic, disk I/O, and CPU time. This IBM Redbooks publication helps you to understand the basics of identifying and tuning the performance of Structured Query Language (SQL) statements using IBM DB2 Universal Database for iSeries. DB2 Universal Database for iSeries provides a comprehensive set of tools that help technical analysts tune SQL queries. The SQL Performance Monitors are part of the set of tools that IBM i5/OS provides for assisting in SQL performance analysis since Version 3 Release 6. These monitors help to analyze database performance problems after SQL requests are run. This book also presents tips and techniques based on the SQL Performance Monitors and other tools, such as Visual Explain. You'll find this guidance helpful in gaining the most out of both DB2 Universal Database for iSeries and query optimizer when using SQL.

In 1978 IBM introduced the System/38 as part of its midrange platform hardware base. One of the many outstanding features of this system was the built-in Relational Database Management System (RDMS) support. The system included a utility for defining databases, screens, and reports. This utility used a form named Data Description Specifications (DDS) to define the database physical (PF) and logical (LF) files (base tables, views, and indexes). In 1988, IBM announced the AS/400. The OS/400 operating system also contained a built-in RDMS, however, IBM offered Structured Query Language (SQL) as an alternative to DDS for creating databases. In addition, SQL Data Manipulation Language (DML) statements were made available as an ad hoc query language tool. These statements could also be embedded and compiled within high level language (HLL) programs. SQL Data Definition Language (DDL) has become the industry standard for defining RDMS databases. Many customers are in the process of modernizing their database definition and the database access. This IBM Redbooks publication will help you understand how to reverse engineer a DDS-created database along, and provides you with tips and techniques for modernizing applications to use SQL as the database access method. Additional Resources on DB2 for i Modernization: