SELECTIVITY ESTIMATION USING NON-QUALIFYING TUPLES

SELECTIVITY ESTIMATION USING NON-QUALIFYING TUPLES

A system includes determination of a query on a table, the query including a first predicate and a second predicate, determination of a sample of the table, the sample comprising a plurality of tuples of the table, determination of a first conditional probability of selecting a tuple of the sample s...

Ausführliche Beschreibung

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Bibliographische Detailangaben
Hauptverfasser: MOERKOTTE, Guido, LEHNER, Wolfgang, HERTZSCHUCH, Axel, WOLF, Florian, FRICKE, Lars, MAY, Norman
Format: Patent
Sprache:eng ; fre ; ger
Schlagworte:
CALCULATING
COMPUTING
COUNTING
ELECTRIC DIGITAL DATA PROCESSING
PHYSICS
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Zusammenfassung:A system includes determination of a query on a table, the query including a first predicate and a second predicate, determination of a sample of the table, the sample comprising a plurality of tuples of the table, determination of a first conditional probability of selecting a tuple of the sample satisfying the first predicate and the second predicate, determination of a second conditional probability of selecting a tuple of the sample satisfying the first predicate and not satisfying the second predicate, adjustment of the first conditional probability based on the second conditional probability, a number of tuples of the sample satisfying the second predicate, a number of tuples of the sample not satisfying the second predicate, and a number of tuples of the sample satisfying the first predicate and not satisfying the second predicate, and determination of a selectivity of the query on the table based on the first adjusted conditional probability.