International Business Machines Corporation
MULTI-PAGE SPLITTING OF A DATABASE INDEX

Abstract:

An improved database-management system determines that a near-capacity leaf page of its database index must be split into multiple pages in order to store newly added index entries. The system determines whether the page should be "multi-split" into more than two pages, the total number of new pages to be added, and the range of indexed values assigned to each new page. These determinations are made as functions of the frequency with which the index page, and other index pages for the same index, have been split in the past, of the data distribution of values indexed by the leaf page, and of the degree of sequentiality of entries added to the leaf page. Leaf pages approaching capacity may also be scheduled for "pre-split" splitting during a period of lower utilization. These multi-split and pre-split operations reduce the numbers of index splits and of corresponding synchronous database-log writes.