Evaluation of rollups with distinct aggregates by using sequence of sorts and partitioning by measures
US6775682B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 26, 2002 |
| Grant date | Aug 10, 2004 |
| Priority date | — |
| Expiry date | Mar 22, 2023 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99943
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Methods are provided for efficiently evaluating database queries including a rollup operator and a distinct aggregate function. Using a sequence of sorts, duplicate record elimination performed on previous sorts at lower, or finer, levels of the rollup operator is taken advantage of by performing subsequent sorts on the preceding sort. Hence, when moving from one rollup level to the next higher level, there are fewer data records to sort with respect to the relevant grouping columns for that level, and thus also fewer duplicate data records to eliminate for purposes of computing the distinct aggregate. Using parallel evaluation, processing of aggregate functions is split among different processing slaves, and the measure of an aggregate function is included as a partitioning key when sending data from one data flow operation to the next data flow operation of a query execution plan. Using parallel evaluation for a query that includes two or more aggregate functions, a measure code corresponding with each aggregate function and associated measure values are included as partitioning keys for enhanced load balancing and parallelization.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.