Browse Prior Art Database

Minimizing Page Faults to a Finite Buffer As Applied to Nested Scans to Satisfy a Relational Join

IP.com Disclosure Number: IPCOM000039848D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01

Publishing Venue

IBM

Related People

Authors:
Lohman, GM McPherson, JA [+details]

Abstract

This invention relates to a method for optimizing page faults to a finite buffer when a sequence of pages is to be accessed repeatedly. More particularly, the method is applied to the nested scanning of a data base to satisfy a relational join operation. In the prior art, it is known that a join between an outer table O and an inner table I finds all values in the join column I.J of table I that match a value of the join column O.J in table O. The nested-loop join technique accomplishes this in the most obvious way, by scanning table I for each successive row in O. Each scan goes through I from beginning to end in either physical order (a DBSPACE scan) or in the logical order of some index (an index scan).