Method and apparatus for predicting selectivity of database...

Details Method and apparatus for predicting selectivity of database... Method and apparatus for predicting selectivity of database...

2008-03-11

2008-03-11

Chace, Christian (Department: 2169)

Data processing: database and file management or data structures

Database design

Data structure types

C707S793000, C707S793000, C707S793000, C707S793000, C707S793000, C707S793000, C707S793000, C715S252000

Reexamination Certificate

active

07343369

ABSTRACT:
A database management system predicts a selectivity for database query conditions requiring a join of records from different tables. The system identifies at least one skewed value in a field specified in the join condition, and constructs, for each skewed value, a set of hypothetical query predicates in which the field specified in the join condition is replaced with a constant equal to the skewed value. The system then predicts the selectivity for the hypothetical predicates, using any appropriate prediction technique. The selectivities of the hypothetical predicates are used to predict a selectivity for the original query.

REFERENCES:
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patent: 5721896 (1998-02-01), Ganguly et al.
patent: 7136850 (2006-11-01), Keller et al.
patent: 2003/0135485 (2003-07-01), Leslie
patent: 2003/0229635 (2003-12-01), Chaudhuri et al.
C. A. Lynch, “Selectivity Estimation and Query Optimization in Large Databases with Highly Skewed Distributions of Column Values”, Proceedings of the 14thVery Large Data Base Conference (1988).

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