Lawrence K Nash

US Patent:

6999958, Feb 14, 2006

Filed:

Jun 7, 2002

Appl. No.:

10/165025

Inventors:

David Glenn Carlson - Rochester MN, US
Kevin James Kathmann - Rochester MN, US
Lawrence Kenneth Nash - Madison WI, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 17/30

US Classification:

707 3, 707 1, 707 4, 707 5

Abstract:

An apparatus, program product and method perform runtime query optimization during execution of a query to select from among multiple available plans, or implementations, capable of implementing the query. The runtime query optimization utilizes a runtime-derived performance criterion to dynamically select from among multiple query implementations. A performance criterion is dynamically evaluated during execution of at least a portion of a query, and one of a plurality of query implementations defined in the query is selected based upon the dynamically-evaluated performance criterion. Once selected, execution of the query is continued using the selected query implementation.