Class StatisticsAggrFunctions.HllFieldReader
java.lang.Object
org.apache.drill.exec.expr.fn.impl.StatisticsAggrFunctions.HllFieldReader
- All Implemented Interfaces:
DrillAggFunc
,DrillFunc
- Enclosing class:
- StatisticsAggrFunctions
The log2m parameter defines the accuracy of the counter. The larger the
log2m the better the accuracy.
accuracy = 1.04/sqrt(2^log2m)
where
log2m - the number of bits to use as the basis for the HLL instance
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Constructor Summary
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Method Summary
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Constructor Details
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HllFieldReader
public HllFieldReader()
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Method Details
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setup
public void setup()Description copied from interface:DrillAggFunc
Initialization for the beginning of the aggregation.- Specified by:
setup
in interfaceDrillAggFunc
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add
public void add()- Specified by:
add
in interfaceDrillAggFunc
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output
public void output()- Specified by:
output
in interfaceDrillAggFunc
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reset
public void reset()- Specified by:
reset
in interfaceDrillAggFunc
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