ApproximateHistogramAggregatorFactory (io.druid:druid 0.8.1 API)

java.lang.Object
- io.druid.query.aggregation.histogram.ApproximateHistogramAggregatorFactory

All Implemented Interfaces:

AggregatorFactory

Direct Known Subclasses:

ApproximateHistogramFoldingAggregatorFactory
```
public class ApproximateHistogramAggregatorFactory
extends Object
implements AggregatorFactory
```

Field Summary

Fields
Modifier and Type	Field and Description
`protected String`	`fieldName`
`protected float`	`lowerLimit`
`protected String`	`name`
`protected int`	`numBuckets`
`protected int`	`resolution`
`protected float`	`upperLimit`

Constructor Summary

Constructors
Constructor and Description
`ApproximateHistogramAggregatorFactory(String name, String fieldName, Integer resolution, Integer numBuckets, Float lowerLimit, Float upperLimit)`

Method Summary

Methods
Modifier and Type	Method and Description
`Object`	`combine(Object lhs, Object rhs)` A method that knows how to combine the outputs of the getIntermediate() method from the Aggregators produced via factorize().
`Object`	`deserialize(Object object)` A method that knows how to "deserialize" the object from whatever form it might have been put into in order to transfer via JSON.
`boolean`	`equals(Object o)`
`Aggregator`	`factorize(ColumnSelectorFactory metricFactory)`
`BufferAggregator`	`factorizeBuffered(ColumnSelectorFactory metricFactory)`
`Object`	`finalizeComputation(Object object)` "Finalizes" the computation of an object.
`Object`	`getAggregatorStartValue()` Returns the starting value for a corresponding aggregator.
`byte[]`	`getCacheKey()`
`AggregatorFactory`	`getCombiningFactory()` Returns an AggregatorFactory that can be used to combine the output of aggregators from this factory.
`Comparator`	`getComparator()`
`String`	`getFieldName()`
`float`	`getLowerLimit()`
`int`	`getMaxIntermediateSize()` Returns the maximum size that this aggregator will require in bytes for intermediate storage of results.
`String`	`getName()`
`int`	`getNumBuckets()`
`List<AggregatorFactory>`	`getRequiredColumns()` Gets a list of all columns that this AggregatorFactory will scan
`int`	`getResolution()`
`String`	`getTypeName()`
`float`	`getUpperLimit()`
`int`	`hashCode()`
`List<String>`	`requiredFields()`
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - name
```
protected final String name
```
  - fieldName
```
protected final String fieldName
```
  - resolution
```
protected final int resolution
```
  - numBuckets
```
protected final int numBuckets
```
  - lowerLimit
```
protected final float lowerLimit
```
  - upperLimit
```
protected final float upperLimit
```
- Constructor Detail
  - ApproximateHistogramAggregatorFactory
```
public ApproximateHistogramAggregatorFactory(String name,
                                     String fieldName,
                                     Integer resolution,
                                     Integer numBuckets,
                                     Float lowerLimit,
                                     Float upperLimit)
```
- Method Detail
  - factorize
```
public Aggregator factorize(ColumnSelectorFactory metricFactory)
```
    Specified by:
    
    factorize in interface AggregatorFactory
  - factorizeBuffered
```
public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
```
    Specified by:
    
    factorizeBuffered in interface AggregatorFactory
  - getComparator
```
public Comparator getComparator()
```
    Specified by:
    
    getComparator in interface AggregatorFactory
  - combine
```
public Object combine(Object lhs,
             Object rhs)
```
    Description copied from interface: AggregatorFactory
    
    A method that knows how to combine the outputs of the getIntermediate() method from the Aggregators produced via factorize(). Note, even though this is called combine, this method's contract *does* allow for mutation of the input objects. Thus, any use of lhs or rhs after calling this method is highly discouraged.
    
    Specified by:
    
    combine in interface AggregatorFactory
    
    Parameters:
    lhs - The left hand side of the combine
    rhs - The right hand side of the combine
    
    Returns:
    an object representing the combination of lhs and rhs, this can be a new object or a mutation of the inputs
  - getCombiningFactory
```
public AggregatorFactory getCombiningFactory()
```
    Description copied from interface: AggregatorFactory
    
    Returns an AggregatorFactory that can be used to combine the output of aggregators from this factory. This generally amounts to simply creating a new factory that is the same as the current except with its input column renamed to the same as the output column.
    
    Specified by:
    
    getCombiningFactory in interface AggregatorFactory
    
    Returns:
    a new Factory that can be used for operations on top of data output from the current factory.
  - getRequiredColumns
```
public List<AggregatorFactory> getRequiredColumns()
```
    Description copied from interface: AggregatorFactory
    
    Gets a list of all columns that this AggregatorFactory will scan
    
    Specified by:
    
    getRequiredColumns in interface AggregatorFactory
    
    Returns:
    AggregatorFactories for the columns to scan of the parent AggregatorFactory
  - deserialize
```
public Object deserialize(Object object)
```
    Description copied from interface: AggregatorFactory
    
    A method that knows how to "deserialize" the object from whatever form it might have been put into in order to transfer via JSON.
    
    Specified by:
    
    deserialize in interface AggregatorFactory
    
    Parameters:
    object - the object to deserialize
    
    Returns:
    the deserialized object
  - finalizeComputation
```
public Object finalizeComputation(Object object)
```
    Description copied from interface: AggregatorFactory
    
    "Finalizes" the computation of an object. Primarily useful for complex types that have a different mergeable intermediate format than their final resultant output.
    
    Specified by:
    
    finalizeComputation in interface AggregatorFactory
    
    Parameters:
    object - the object to be finalized
    
    Returns:
    the finalized value that should be returned for the initial query
  - getName
```
public String getName()
```
    Specified by:
    
    getName in interface AggregatorFactory
  - getFieldName
```
public String getFieldName()
```
  - getResolution
```
public int getResolution()
```
  - getLowerLimit
```
public float getLowerLimit()
```
  - getUpperLimit
```
public float getUpperLimit()
```
  - getNumBuckets
```
public int getNumBuckets()
```
  - requiredFields
```
public List<String> requiredFields()
```
    Specified by:
    
    requiredFields in interface AggregatorFactory
  - getCacheKey
```
public byte[] getCacheKey()
```
    Specified by:
    
    getCacheKey in interface AggregatorFactory
  - getTypeName
```
public String getTypeName()
```
    Specified by:
    
    getTypeName in interface AggregatorFactory
  - getMaxIntermediateSize
```
public int getMaxIntermediateSize()
```
    Description copied from interface: AggregatorFactory
    
    Returns the maximum size that this aggregator will require in bytes for intermediate storage of results.
    
    Specified by:
    
    getMaxIntermediateSize in interface AggregatorFactory
    
    Returns:
    the maximum number of bytes that an aggregator of this type will require for intermediate result storage.
  - getAggregatorStartValue
```
public Object getAggregatorStartValue()
```
    Description copied from interface: AggregatorFactory
    
    Returns the starting value for a corresponding aggregator. For example, 0 for sums, - Infinity for max, an empty mogrifier
    
    Specified by:
    
    getAggregatorStartValue in interface AggregatorFactory
    
    Returns:
    the starting value for a corresponding aggregator.
  - equals
```
public boolean equals(Object o)
```
    Overrides:
    
    equals in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class ApproximateHistogramAggregatorFactory

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

name

fieldName

resolution

numBuckets

lowerLimit

upperLimit

Constructor Detail

ApproximateHistogramAggregatorFactory

Method Detail

factorize

factorizeBuffered

getComparator

combine

getCombiningFactory

getRequiredColumns

deserialize

finalizeComputation

getName

getFieldName

getResolution

getLowerLimit

getUpperLimit

getNumBuckets

requiredFields

getCacheKey

getTypeName

getMaxIntermediateSize

getAggregatorStartValue

equals

hashCode

toString