Data processing: database and file management or data structures – Database design – Data structure types
Patent
1996-12-27
1998-10-06
Black, Thomas G.
Data processing: database and file management or data structures
Database design
Data structure types
707 3, 707 4, 707 5, 707 6, G06F 1730
Patent
active
058192557
ABSTRACT:
A system and method for optimizing a database query with improved performance enhancements is herein disclosed. The database query consists of one or more logical expressions. Through the repeated application of one or more rules, the logical expressions are transformed into physical expressions and in some cases, execution plans that implement the database query. Each expression has associated with it a set of group attributes that specifies its characteristic inputs and outputs and a cost that estimates the computational expense for executing the expression. The group attributes are used to categorize similar expressions into groups that are stored in a search data structure. They are also used to track duplicate expressions. The cost associated with an expression is used to guide the search process to consider those expressions that will produce low cost plans. The cost is estimated in accordance with a six-fold criteria with each criterion weighted to account for the context of the expression and the application's particular computing environment. The query optimizer is rule-based including transformation and implementation rules that are used to perform transformations on the logical expressions in a subproblem in order to produce a plan. A OnceGuidance guidance method is used to select a set of rules in certain cases that prevent the regeneration of an existing expression.
REFERENCES:
patent: 4769772 (1988-09-01), Dwyer
patent: 4829427 (1989-05-01), Green
patent: 5228116 (1993-07-01), Harris et al.
K. Mikkilineni and S. Su, "A Dynamic Interquery Optimization Method For Achieving Data Sharing Among Concurrent Queries", Ieee Comput. Soc. Press, pp. 477-486, Aug. 14, 1988.
Celis Pedro
Vaishnav Jay
Zeller Hansjorg
Black Thomas G.
Lewis Cheryl
Tandem Computers Inc.
Williams Gary S.
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