System and method for performing an efficient join operation on large tables with a small main memory
US5666525A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 21, 1995 |
| Grant date | Sep 9, 1997 |
| Priority date | — |
| Expiry date | Sep 21, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99932
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A technique for efficiently joining multiple large tables in a database system with a processor using a small main memory. The technique utilizes a join index and minimizes the number of Input/Output operations while maximizing the use of the small main memory through a buffer allocation process. The technique partitions available main memory into buffers and assigns conditions to the buffers to ensure that each buffer will receive a substantially equal amount of data in the join result. The technique then processes each input table separately based on the assigned conditions and sequentially reads and processes each input table. The output is vertically fragmented with one fragment for each input table which further allows the individual processing of each input table. Also described is a method for creating a join index if one is not present.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.