Techniques for optimizing outer joins
US8868545B2 · kind B2 · utility
8Cited by
17References
20Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Dec 29, 2011 |
| Grant date | Oct 21, 2014 |
| Priority date | — |
| Expiry date | Oct 2, 2032 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F16/24544
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Techniques for optimizing outer joins in database operations are provided. In an embodiment, a query having an outer join with a GROUP BY clause is rewritten and expanded to expand a first level partition of that GROUP BY clause to produce a modified query. In another situation, rows associated with processing a query are each row split and then hashed based at least in part on attributes of the outer join predicate. A left outer join is performed and a global aggregation processed to produce a spooled table to process the query.
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