IMS (DL/I) Data-base Organization and Performance

Book excerpt: This book provides a detailed understanding of DL/I data bases and how they perform. It bridges the gap between a beginning knowledge of DL/I data-base concepts and the very detailed knowledge required for data-base design and tuning studies, and it does this by explaining the major concepts and considerations in data-base organization and performance. It explains the reasons behind these concepts and considerations so that the reader can the make knowledgeable, reasonable choices and trade-offs in selecting logical and physical design parameters for data-base implementation and tuning. The name of the game is to reduce the number of physical I/Os required to process a job. Minimizing the physical I/Os is accomplished by appropriate data-base and application program design.