11.1.1 Allocating index global buffers

A dedicated global buffer should be allocated to an index that is accessed frequently, especially an index for which a cluster key or UNIQUE is specified. This enables the index to be made resident, thereby reducing the number of input/output operations required to access the index.

A dedicated global buffer that is allocated to an index is managed independently of the global buffer for the user RDAREAs that contain the table rows. This means that index pages and data pages are not shared within a global buffer. If the same global buffer is allocated to more than one index or table, information for one index may be swapped out of the global buffer in the event a large amount of data for another table is placed in it temporarily.

The following figure shows an overview of a dedicated global buffer for an index.

Figure 11-1 Overview of global buffer for an index

[Figure]