Estimation of join fanout using augmented histogram
AssigneeInternational Business Machines Corporation
InventorAbdo Esmail Abdo
Life of this patent
Estimating the term…
Abstract
In processing a query including a selection criterion on one or more attributes of a relation, a join fanout statistic is generated using an equi-width histogram for the join attribute, that is augmented to identify the most frequent values in the join attribute. In this way, a more accurate join fanout statistic may be generated as compared to statistics generated using formulas, with favorable storage and resource consumption as compared to a conventional index.
Claims17
A method for estimating statistics on an attribute of a relation, comprising
- forming a histogram of said attribute of said relation, the histogram being augmented to identify the most frequent values of an attribute,
- evaluating said histogram in connection with a criterion for retrieval of data from a relation.
A computer system for implementing a relational database system and performing a user query on said relational database system, comprising
- storage for relations of said relational database system, and a histogram of an attribute of a first of said relations, the histogram being augmented to identify the most frequent values of an attribute in said first relation,
- a computing circuit for implementing said relational database system, said computing circuit computing a statistic on said attribute by evaluating said histogram in connection with a criterion for retrieval of data from a relation.
A program product for estimating statistics on an attribute of a relation, comprising
- a program of instructions executable on a computer system to form a histogram of said attribute of said relation, the histogram being augmented to identify the most frequent values of an attribute, and evaluate said histogram in connection with a criterion for retrieval of data from a relation, and
- a signal bearing medium bearing the program.
Dependencies are inferred from the claim text.