Look-ahead predicate generation for join costing and optimization

A relational database system analyzes each potential join in a query, to determine whether a relation involved in the join is subject to a selection criterion, and evaluate whether that selection criterion or the join per se effects a join reduction. The computational expense of generating a look-ah...

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Bibliographic Details
Main Authors ABDO ABDO E, BESTGEN ROBERT J, DIETEL JOHN D
Format Patent
LanguageEnglish
Published 21.07.2005
Edition7
Subjects
CALCULATING
COMPUTING
COUNTING
ELECTRIC DIGITAL DATA PROCESSING
PHYSICS
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Summary:A relational database system analyzes each potential join in a query, to determine whether a relation involved in the join is subject to a selection criterion, and evaluate whether that selection criterion or the join per se effects a join reduction. The computational expense of generating a look-ahead predicate comprising the tuples of the second relation matching any applicable selection criterion, is compared to the computational savings that result from the join reduction. The most beneficial look-ahead predicate among all potential joins of relations in the query is identified through iterative analysis of all possible joins. Thereafter, membership in the look-ahead predicate is added as a selection criterion on the first relation, and further iterative analysis is performed of all possible joins of the remaining relations and the look-ahead predicate, to iteratively identify additional joins in the query that benefit from the formation of the look-ahead predicate, and potentially form further look-ahead predicates.
Bibliography:Application Number: US20040758485