System and method for cardinality estimation based on query execution feedback
First Claim
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1. A method for estimating a cardinality of an expression, the method comprising:
- matching the expression with a stored expression;
retrieving statistics associated with the stored expression; and
estimating the cardinality of the expression based on the statistics.
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Abstract
During query execution, statistics associated with expressions are observed. Such observed statistics preferably include the cardinality of each expression. The observed statistics are submitted to an expression manager as feedback from the executed query. The statistics are preferably stored for use in estimating the cardinality of execution plans for future queries.
47 Citations
20 Claims
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1. A method for estimating a cardinality of an expression, the method comprising:
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matching the expression with a stored expression;
retrieving statistics associated with the stored expression; and
estimating the cardinality of the expression based on the statistics. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A computer readable medium having stored thereon computer readable instructions for performing the following steps:
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matching an expression with a stored expression;
retrieving statistics associated with the stored expression; and
estimating the cardinality of the expression based on the statistics. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A system for estimating a cardinality of an expression, the system comprising:
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an expression manager for performing the steps of;
matching the expression with a stored expression; and
retrieving statistics associated with the stored expression; and
an optimizer for performing the step of estimating the cardinality of the expression based on the statistics. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification