TECHNIQUE FOR FACTORING UNCERTAINTY INTO COST-BASED QUERY OPTIMIZATION

TECHNIQUE FOR FACTORING UNCERTAINTY INTO COST-BASED QUERY OPTIMIZATION

A technique for factoring uncertainty into cost-based query optimization includes: determining the degree of uncertainty involved in the cost estimates for the query, determining the degree of sensitivity the query has to that uncertainty, and determining if there is an access path that performs wel...

Ausführliche Beschreibung

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Bibliographische Detailangaben
Hauptverfasser: PURCELL TERENCE P, BEAVIN THOMAS A, ALPERS JASON L, GUO SHUANGLIN, BOSSMAN PATRICK D
Format: Patent
Sprache:eng
Schlagworte:
CALCULATING
COMPUTING
COUNTING
ELECTRIC DIGITAL DATA PROCESSING
PHYSICS
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Beschreibung
Zusammenfassung:A technique for factoring uncertainty into cost-based query optimization includes: determining the degree of uncertainty involved in the cost estimates for the query, determining the degree of sensitivity the query has to that uncertainty, and determining if there is an access path that performs well across the range of possible conditions that could occur at execution time, reducing the risk of performance spikes and performance volatility. If such an access path exists, select that access path; if not, perform parametric query optimization or query re-optimization.