Operator for correlated predicates in a query
US6560595B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 15, 1999 |
| Grant date | May 6, 2003 |
| Priority date | — |
| Expiry date | Nov 15, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99944
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A correlation operator &THgr; provides a way for the results of sub-queries to be correlated. The correlation operator &THgr; has an implied existential quantifier property (i.e., a “for some” property) and is satisfied if any record matches its sub-query. If no record is found that matches the correlation operator &THgr;'s sub-query, then the correlation operator &THgr; query fails. The implicit existential quantifier property of the correlation operator &THgr; can be converted into a universal quantifier property (i.e., a “for all” property) by transformation of the query.The correlation operator &THgr; uses an algebra to resolve into flags attached to appropriate operators in the sub-query. After the correlation operator &THgr; is eliminated from the query, the query can be performed. The operator flags perform the correlation as part of the sub-query.The correlation operator &THgr; can be inserted explicitly by the user if she knows what data she desires to be correlated. Alternatively, the correlation operator can be inserted by the schema automatically to improve the expected results of the query.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.