Star/join query optimization
US5960428A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 28, 1997 |
| Grant date | Sep 28, 1999 |
| Priority date | — |
| Expiry date | Aug 28, 2017 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99934
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Unwieldy star/join queries are performed more efficiently using a filtered fact table. Suitable queries include star/join queries with a large fact table joined with multiple subsidiary dimension tables, where indices exist over fact table join columns. The query is analyzed to prepare a query plan for the dimension table accesses. This plan is supplemented by adding nested loop join operations, where the inner table is a dimension table plan and the outer table is an index scan performed over a fact table index of the join column with the dimension table. The plan is also supplemented by filtering records resulting from the nested loop joins using a sequence of dynamic bit vectors, ultimately yielding a list of probable fact table records. The plan is further supplemented by fetching these records to construct a distilled fact which is used, instead of the large original table, to execute the query in considerably less time. If desired, the supplemented query plan and other competing approaches may studied to provide cost estimates, with the least costly approach being actually implemented.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.