Performing an outer join between a small table and a large table
US8600994B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 2, 2010 |
| Grant date | Dec 3, 2013 |
| Priority date | — |
| Expiry date | Aug 7, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F16/40
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A small table S is outer joined to a large table L on a join condition on a database system with a plurality B of parallel units (PUs). S and L are partitioned across the PUs. Each row in S has a unique row-id. Each row of S is duplicated on all PUs to form Sdup. On each PU, dangling rows in S that do not have a match in L under the join condition are identified and the row-ids of the dangling rows are saved in Tredis. Tredis is partitioned across the PUs. P is formed from dangling rows of S whose corresponding entries in Tredis appear in all PUs. A result is produced by unioning P and I. I is formed by inner joining non-dangling rows of S with L. The result is saved.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.