System and method for performing an efficient join operation
US5802357A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 16, 1996 |
| Grant date | Sep 1, 1998 |
| Priority date | — |
| Expiry date | Apr 16, 2016 |
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. Three embodiments of the technique are described all of which use the parallel-merge operation. The first technique, slam-join, is for joining two tables and does not require any pre-allocation of buffers to perform the join operation. The second technique, multi-slam-join, is for joining three or more tables and adds the parallel-merge technique to a join technique which partitions memory to be used for an efficient join operation. The third technique, called parallel-join, processes each input table completely independently using the parallel-merge technique. The parallel-merge technique identifies the lowest value from multiple files and orders all the values from lowest to highest. This enables sequential reading of input files saving I/O operations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.