Union all rewrite for aggregate queries with grouping sets
US7379933B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 27, 2002 |
| Grant date | May 27, 2008 |
| Priority date | — |
| Expiry date | Jun 8, 2024 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99935
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Query rewrite techniques are provided for rewriting an aggregate query with multiple groupings using multiple summary tables. The rewrite is accomplished by expanding the aggregate query into an equivalent UNION ALL query with multiple subqueries, each containing a single grouping. One or more of the subqueries is then rewritten to reference a summary table. Thus, a grouping of an aggregate query is derived by executing a subquery that either scans the summary table for the grouping, like in the exact-match mode, or by performing a roll-up operation, like in the roll-up mode. In addition, if the grouping of some of the subqueries cannot be derived from a summary table, subqueries are combined into another subquery that computes groupings from the base tables of the aggregate query.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.