The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 30, 1999
Filed:
Feb. 28, 1997
Thomas Abel Beavin, Milpitas, CA (US);
Balakrishna Raghavendra Iyer, San Jose, CA (US);
Akira Shibamiya, Los Altos, CA (US);
Hong Sang Tie, Morgan Hill, CA (US);
Min Wang, San Jose, CA (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
The system, method, and program of this invention collects multi-column statistics, by a database management system, to reflect a relationship among multiple columns of a table in a relational database. These statistics are stored in the system catalog, and are used during query optimization to obtain an estimate of the number of qualifying rows when a query has predicates on multiple columns of a table. A multi-column linear quantile statistic is collected by dividing the data of multiple columns into sub-ranges where each sub-range has approximately an even distribution of data, and determining a frequency and cardinality of each sub-range. A multi-column polygonal quantile statistic is collected by dividing the data of multiple columns into sub-spaces where each sub-space contains approximately the same number of tuples, and determining a frequency and cardinality of each sub-space. The system catalog is accessed for the stored multi-column linear quantile statistic for a query having a single range predicate and at least one equal predicate to determine the selectivity value for the predicates of the query. The system catalog is accessed for the stored multi-column polygonal quantile statistic for a query having more than one range predicate. These statistics are used in various ways to determine the selectivity value for the predicates of the query.