io.crate.operation.aggregation.impl

Class ArbitraryAggregation

java.lang.Object

io.crate.operation.aggregation.AggregationFunction<java.lang.Object,java.lang.Object>

io.crate.operation.aggregation.impl.ArbitraryAggregation

All Implemented Interfaces:

FunctionImplementation<Function>

public class ArbitraryAggregation
extends AggregationFunction<java.lang.Object,java.lang.Object>

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	NAME

Method Summary

Methods

Modifier and Type	Method and Description
FunctionInfo	info()
java.lang.Object	iterate(RamAccountingContext ramAccountingContext, java.lang.Object state, Input... args) the "aggregate" function.
java.lang.Comparable	newState(RamAccountingContext ramAccountingContext) Called once per "aggregation cycle" to create an initial partial-state-value.
DataType	partialType()
java.lang.Object	reduce(RamAccountingContext ramAccountingContext, java.lang.Object state1, java.lang.Object state2) This function merges two aggregation states together and returns that merged state.
static void	register(AggregationImplModule mod)
java.lang.Object	terminatePartial(RamAccountingContext ramAccountingContext, java.lang.Object state) Called to transform partial states into their final form.

Methods inherited from class io.crate.operation.aggregation.AggregationFunction

normalizeSymbol

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NAME

public static final java.lang.String NAME

See Also:

Constant Field Values

Method Detail

register

public static void register(AggregationImplModule mod)

info

public FunctionInfo info()

partialType

public DataType partialType()

Specified by:

partialType in class AggregationFunction<java.lang.Object,java.lang.Object>

newState

public java.lang.Comparable newState(RamAccountingContext ramAccountingContext)

Description copied from class: AggregationFunction

Called once per "aggregation cycle" to create an initial partial-state-value.

Specified by:

newState in class AggregationFunction<java.lang.Object,java.lang.Object>

Parameters:

ramAccountingContext - used to account the memory used for the state.

Returns:

a new state instance or null

iterate

public java.lang.Object iterate(RamAccountingContext ramAccountingContext,
                       java.lang.Object state,
                       Input... args)

Description copied from class: AggregationFunction

the "aggregate" function.

Specified by:

iterate in class AggregationFunction<java.lang.Object,java.lang.Object>

Parameters:

ramAccountingContext - used to account for additional memory usage if the state grows in size

state - the previous aggregation state

args - arguments / input values matching the types of FunctionInfo.argumentTypes. These are usually used to increment/modify the previous state

Returns:

The new/changed state. This might be either a new instance or the same but mutated instance. Users of the AggregationFunction should always use the return value, but must be aware that the input state might have changed too.

reduce

public java.lang.Object reduce(RamAccountingContext ramAccountingContext,
                      java.lang.Object state1,
                      java.lang.Object state2)

Description copied from class: AggregationFunction

This function merges two aggregation states together and returns that merged state. This is used in a distributed aggregation workflow where 2 partial aggregations are reduced into 1 partial aggregation

Specified by:

reduce in class AggregationFunction<java.lang.Object,java.lang.Object>

Returns:

the reduced state. This might be a new instance or a mutated state1 or state2.

terminatePartial

public java.lang.Object terminatePartial(RamAccountingContext ramAccountingContext,
                                java.lang.Object state)

Description copied from class: AggregationFunction

Called to transform partial states into their final form. This might result in a loss of "meta data" that was necessary to compute the final value.

Specified by:

terminatePartial in class AggregationFunction<java.lang.Object,java.lang.Object>