Cardinality estimation of joins
US7299226B2 · kind B2 · utility
9Cited by
1References
20Claims
0Family size
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Key dates
| Filing date | Jun 19, 2003 |
| Grant date | Nov 20, 2007 |
| Priority date | — |
| Expiry date | Aug 17, 2024 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99937
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method of estimating cardinality of a join of tables using multi-column density values and additionally using coarser density values of a subset of the multi-column density attributes. In one embodiment, the subset of attributes for the coarser densities is a prefix of the set of multi-column density attributes. A number of tuples from each table that participate in the join may be estimated using densities of the subsets. The cardinality of the join can be estimated using the multi-column density for each table and the estimated number of tuples that participate in the join from each table.
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