Techniques of optimizing queries using NULL expression analysis
US7739219B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 8, 2006 |
| Grant date | Jun 15, 2010 |
| Priority date | — |
| Expiry date | May 3, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F16/24537
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method for optimizing queries is described. A query, which includes a first expression for determining whether each of a set of values evaluates to NULL or NOT NULL, is received. At compile-time, a first representation of the query is generated, where the first representation indicates that the query is to be performed based on the first expression. Based on the first expression, a second expression is determined. The second expression is such that the first expression would evaluate to any NOT NULL value if and only if the second expression would evaluate to any NOT NULL value. The second expression, when evaluated, is much more computationally efficient compared with the evaluation of the first expression. Based on the first representation, a second representation of the query is generated, where the second representation indicates that the query is to be performed based on the second expression. Thereafter, the query is executed based on the second representation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.