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:
Dec. 22, 2009
Filed:
Apr. 25, 2007
Thierry Cruanes, Foster City, CA (US);
Uri Shaft, Castro Valley, CA (US);
Hong Su, Foster City, CA (US);
Benoit Dageville, Foster City, CA (US);
Sunil P. Chakkappen, Foster City, CA (US);
Mohamed Zait, San Jose, CA (US);
Thierry Cruanes, Foster City, CA (US);
Uri Shaft, Castro Valley, CA (US);
Hong Su, Foster City, CA (US);
Benoit Dageville, Foster City, CA (US);
Sunil P. Chakkappen, Foster City, CA (US);
Mohamed Zait, San Jose, CA (US);
Oracle International Corporation, Redwood Shores, CA (US);
Abstract
A method and apparatus for approximating a database statistic, such as the number of distinct values (NDV) is provided. To approximate the NDV for a portion of a table, a synopsis of distinct values is constructed. Each value in the portion is mapped to a domain of values. The mapping function is implemented with a uniform hash function, in one embodiment. If the resultant domain value does not exist in the synopsis, the domain value is added to the synopsis. If the synopsis reaches its capacity, a portion of the domain values are discarded from the synopsis. The statistic is approximated based on the number (N) of domain values in the synopsis and the portion of the domain that is represented in the synopsis relative to the size of the domain.