Generating a query plan for estimating a number of unique attributes in a database
US9576027B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 27, 2008 |
| Grant date | Feb 21, 2017 |
| Priority date | — |
| Expiry date | Apr 27, 2035 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F16/24524
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In a method for generating a query plan for estimating a number of unique entry counts of an attribute in a database, a sample of entries in the database is identified, at least one of a sampling percent and a coefficient of variance of the entries in the sample is identified, and a skewness of the entries in the sample is calculated. In addition, at least one of a plurality of estimators is selected based upon the skewness of the entries and at least one of the sampling percent and the coefficient of variance of the entries in the sample. Moreover, a query plan is generated from the selected at least one of the plurality of estimators. A query optimizer for performing the method is provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.