System, method, and computer program product for progressive query processing
US7716215B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 14, 2007 |
| Grant date | May 11, 2010 |
| Priority date | — |
| Expiry date | Oct 28, 2028 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99935
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method, system, and computer program product to make query processing more robust in the face of optimization errors. The invention validates the statistics and assumptions used for compiling a query as the query is executed and, when necessary, progressively re-optimizes the query in mid-execution based on the knowledge learned during its partial execution. The invention selectively places a number of CHECK operators in a query execution plan to validate the optimizer's cardinality estimates against actual cardinalities. Errors beyond a threshold trigger re-optimization, and the optimizer decides whether the old plan is still optimal and whether to re-use previously computed results. The invention addresses arbitrary SQL queries whose plans can contain sub-queries, updates, trigger checking, and view maintenance operations. The invention can handle concurrent update transactions or updates of common sub-expressions in a query execution plan without compromising consistency and isolation as locking information is tied to the record ID.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.