Physical Database Design

7.8 Range Partitioning and Clustering Indexes 139

7.8 Range Partitioning and Clustering Indexes

Clustering indexes dramatically improve the efficiency of scans by reducing the I/O

required on the base table by ensuring that records with similar key data are located near

each other within the table storage. As described earlier, range partitioning implicitly

clusters data according to the range partition. However, the design of range partitioning

is often driven predominantly by administration needs (utility isolation, roll-in, and

roll-out), while clustering design is often driven by performance goals. The goals can

therefore conflict. Optimal scans are ...