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Adaptive Path Selection for Query With Input Variables

IP.com Disclosure Number: IPCOM000036179D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-28

Publishing Venue

IBM

Related People

Authors:
Gan, C Lee, YH Yu, PS [+details]

Abstract

A technique is described wherby a new approach to access path selection for queries with input variables is provided. Rather than one pre- selected fixed access path, this proposed approach preselects a number of optimal access paths with one of these adopted for execution based on the run-time input variable values. Under the proposed approach, the selectivity of predicates where only constants are involved is estimated by query optimizer as the traditional approach. However, for a predicate where input variable is involved, we estimate the selectivity after the value of variable is determined instead of using default value.