VarianceAggregatorFactory (io.druid:druid 0.10.0 API)

java.lang.Object
- io.druid.query.aggregation.AggregatorFactory
- - io.druid.query.aggregation.variance.VarianceAggregatorFactory

All Implemented Interfaces:

Cacheable

Direct Known Subclasses:

VarianceFoldingAggregatorFactory
```
public class VarianceAggregatorFactory
extends AggregatorFactory
```

Field Summary

Fields
Modifier and Type	Field and Description
`protected static byte`	`CACHE_TYPE_ID`
`protected String`	`estimator`
`protected String`	`fieldName`
`protected boolean`	`isVariancePop`
`protected String`	`name`

Constructor Summary

Constructors
Constructor and Description
`VarianceAggregatorFactory(String name, String fieldName)`
`VarianceAggregatorFactory(String name, String fieldName, String estimator, String inputType)`

Method Summary

All Methods Instance Methods Concrete 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.
`byte[]`	`getCacheKey()` Get a byte array used as a cache key.
`AggregatorFactory`	`getCombiningFactory()` Returns an AggregatorFactory that can be used to combine the output of aggregators from this factory.
`Comparator`	`getComparator()`
`String`	`getEstimator()`
`String`	`getFieldName()`
`String`	`getInputType()`
`int`	`getMaxIntermediateSize()` Returns the maximum size that this aggregator will require in bytes for intermediate storage of results.
`AggregatorFactory`	`getMergingFactory(AggregatorFactory other)` Returns an AggregatorFactory that can be used to merge the output of aggregators from this factory and other factory.
`String`	`getName()`
`List<AggregatorFactory>`	`getRequiredColumns()` Gets a list of all columns that this AggregatorFactory will scan
`String`	`getTypeName()`
`int`	`hashCode()`
`List<String>`	`requiredFields()`
`String`	`toString()`

Methods inherited from class io.druid.query.aggregation.AggregatorFactory
mergeAggregators

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

- Field Detail
  - CACHE_TYPE_ID
```
protected static final byte CACHE_TYPE_ID
```
    See Also:
    
    Constant Field Values
  - fieldName
```
protected final String fieldName
```
  - name
```
protected final String name
```
  - estimator
```
protected final String estimator
```
  - isVariancePop
```
protected final boolean isVariancePop
```
- Constructor Detail
  - VarianceAggregatorFactory
```
public VarianceAggregatorFactory(String name,
                                 String fieldName,
                                 String estimator,
                                 String inputType)
```
  - VarianceAggregatorFactory
```
public VarianceAggregatorFactory(String name,
                                 String fieldName)
```
- Method Detail
  - getTypeName
```
public String getTypeName()
```
    Specified by:
    
    getTypeName in class AggregatorFactory
  - getMaxIntermediateSize
```
public int getMaxIntermediateSize()
```
    Description copied from class: AggregatorFactory
    
    Returns the maximum size that this aggregator will require in bytes for intermediate storage of results.
    
    Specified by:
    
    getMaxIntermediateSize in class AggregatorFactory
    
    Returns:
    
    the maximum number of bytes that an aggregator of this type will require for intermediate result storage.
  - factorize
```
public Aggregator factorize(ColumnSelectorFactory metricFactory)
```
    Specified by:
    
    factorize in class AggregatorFactory
  - factorizeBuffered
```
public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
```
    Specified by:
    
    factorizeBuffered in class AggregatorFactory
  - getCombiningFactory
```
public AggregatorFactory getCombiningFactory()
```
    Description copied from class: 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 class 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 class: AggregatorFactory
    
    Gets a list of all columns that this AggregatorFactory will scan
    
    Specified by:
    
    getRequiredColumns in class AggregatorFactory
    
    Returns:
    
    AggregatorFactories for the columns to scan of the parent AggregatorFactory
  - getMergingFactory
```
public AggregatorFactory getMergingFactory(AggregatorFactory other)
                                    throws AggregatorFactoryNotMergeableException
```
    Description copied from class: AggregatorFactory
    
    Returns an AggregatorFactory that can be used to merge the output of aggregators from this factory and other factory. This method is relevant only for AggregatorFactory which can be used at ingestion time.
    
    Overrides:
    
    getMergingFactory in class AggregatorFactory
    
    Returns:
    
    a new Factory that can be used for merging the output of aggregators from this factory and other.
    
    Throws:
    
    AggregatorFactoryNotMergeableException
  - getComparator
```
public Comparator getComparator()
```
    Specified by:
    
    getComparator in class AggregatorFactory
  - combine
```
public Object combine(Object lhs,
                      Object rhs)
```
    Description copied from class: 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 class 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
  - finalizeComputation
```
public Object finalizeComputation(Object object)
```
    Description copied from class: 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 class AggregatorFactory
    
    Parameters:
    
    object - the object to be finalized
    
    Returns:
    
    the finalized value that should be returned for the initial query
  - deserialize
```
public Object deserialize(Object object)
```
    Description copied from class: 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 class AggregatorFactory
    
    Parameters:
    
    object - the object to deserialize
    
    Returns:
    
    the deserialized object
  - getFieldName
```
public String getFieldName()
```
  - getName
```
public String getName()
```
    Specified by:
    
    getName in class AggregatorFactory
  - getEstimator
```
public String getEstimator()
```
  - getInputType
```
public String getInputType()
```
  - requiredFields
```
public List<String> requiredFields()
```
    Specified by:
    
    requiredFields in class AggregatorFactory
  - getCacheKey
```
public byte[] getCacheKey()
```
    Description copied from interface: Cacheable
    
    Get a byte array used as a cache key.
    
    Returns:
    
    a cache key
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - equals
```
public boolean equals(Object o)
```
    Overrides:
    
    equals in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object

Class VarianceAggregatorFactory

Field Summary

Constructor Summary

Method Summary

Methods inherited from class io.druid.query.aggregation.AggregatorFactory

Methods inherited from class java.lang.Object

Field Detail

CACHE_TYPE_ID

fieldName

name

estimator

isVariancePop

Constructor Detail

VarianceAggregatorFactory

VarianceAggregatorFactory

Method Detail

getTypeName

getMaxIntermediateSize

factorize

factorizeBuffered

getCombiningFactory

getRequiredColumns

getMergingFactory

getComparator

combine

finalizeComputation

deserialize

getFieldName

getName

getEstimator

getInputType

requiredFields

getCacheKey

toString

equals

hashCode