org.apache.datasketches.pig.kll

Class UnionSketch

java.lang.Object

org.apache.pig.EvalFunc<org.apache.pig.data.DataByteArray>

org.apache.datasketches.pig.kll.UnionSketch

All Implemented Interfaces:

org.apache.pig.Accumulator<org.apache.pig.data.DataByteArray>, org.apache.pig.Algebraic

public class UnionSketch
extends org.apache.pig.EvalFunc<org.apache.pig.data.DataByteArray>
implements org.apache.pig.Accumulator<org.apache.pig.data.DataByteArray>, org.apache.pig.Algebraic

This UDF is to merge sketches. This class implements both the Accumulator and Algebraic interfaces for performance optimization.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	UnionSketch.Final Class used to calculate the final pass of an Algebraic union operation.
static class	UnionSketch.Initial Class used to calculate the initial pass of an Algebraic sketch operation.
static class	UnionSketch.Intermediate Class used to calculate the intermediate pass of an Algebraic union operation.

Nested classes/interfaces inherited from class org.apache.pig.EvalFunc

org.apache.pig.EvalFunc.SchemaType

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

Constructors

Constructor and Description
UnionSketch() Default constructor.
UnionSketch(String kStr) Constructor with explicit k as string.

Method Summary

Modifier and Type	Method and Description
void	accumulate(org.apache.pig.data.Tuple inputTuple) An Accumulator version of the standard exec() method.
void	cleanup() Cleans up the UDF state after being called using the Accumulator interface.
org.apache.pig.data.DataByteArray	exec(org.apache.pig.data.Tuple inputTuple) Top-level exec function.
String	getFinal()
String	getInitial()
String	getIntermed()
org.apache.pig.data.DataByteArray	getValue() Returns the result of the Union that has been built up by multiple calls to accumulate(org.apache.pig.data.Tuple).

Methods inherited from class org.apache.pig.EvalFunc

allowCompileTimeCalculation, finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLoadCaster, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, getSchemaType, getShipFiles, isAsynchronous, needEndOfAllInputProcessing, outputSchema, progress, setEndOfAllInput, setInputSchema, setPigLogger, setReporter, setUDFContextSignature, warn

Methods inherited from class java.lang.Object

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

Constructor Detail

UnionSketch

public UnionSketch()

Default constructor. Assumes default k.

UnionSketch

public UnionSketch(String kStr)

Constructor with explicit k as string.

Parameters:

kStr - string representation of k

Method Detail

exec

public org.apache.pig.data.DataByteArray exec(org.apache.pig.data.Tuple inputTuple)
                                       throws IOException

Top-level exec function. This method accepts an input Tuple containing a Bag of one or more inner Sketch Tuples and returns a single updated Sketch as a DataByteArray.

Types are in the form: Java data type: Pig DataType

Input Tuple

• Tuple: TUPLE (Must contain only one field)
  • index 0: DataBag: BAG (May contain 0 or more Inner Tuples)
    • index 0: Tuple: TUPLE Sketch Tuple
    • ...
    • index n-1: Tuple: TUPLE Sketch Tuple

Sketch Tuple

• Tuple: TUPLE (Contains exactly 1 field)
  • index 0: DataByteArray: BYTEARRAY = The serialization of a Sketch object.

Specified by:

exec in class org.apache.pig.EvalFunc<org.apache.pig.data.DataByteArray>

Parameters:

inputTuple - A tuple containing a single bag, containing Sketch Tuples

Returns:

serialized sketch

Throws:

IOException

See Also:

"org.apache.pig.EvalFunc.exec(org.apache.pig.data.Tuple)"

accumulate

public void accumulate(org.apache.pig.data.Tuple inputTuple)
                throws IOException

An Accumulator version of the standard exec() method. Like exec(), accumulator is called with a bag of Sketch Tuples. Unlike exec(), it doesn't serialize the sketch at the end. Instead, it can be called multiple times, each time with another bag of Sketch Tuples to be input to the Union.

Specified by:

accumulate in interface org.apache.pig.Accumulator<org.apache.pig.data.DataByteArray>

Parameters:

inputTuple - A tuple containing a single bag, containing Sketch Tuples.

Throws:

IOException - by Pig

See Also:

exec(org.apache.pig.data.Tuple), "org.apache.pig.Accumulator.accumulate(org.apache.pig.data.Tuple)"

getValue

public org.apache.pig.data.DataByteArray getValue()

Returns the result of the Union that has been built up by multiple calls to accumulate(org.apache.pig.data.Tuple).

Specified by:

getValue in interface org.apache.pig.Accumulator<org.apache.pig.data.DataByteArray>

Returns:

serialized sketch

See Also:

"org.apache.pig.Accumulator.getValue()"

cleanup

public void cleanup()

Cleans up the UDF state after being called using the Accumulator interface.

Specified by:

cleanup in interface org.apache.pig.Accumulator<org.apache.pig.data.DataByteArray>

See Also:

"org.apache.pig.Accumulator.cleanup()"

getInitial

public String getInitial()

Specified by:

getInitial in interface org.apache.pig.Algebraic

getIntermed

public String getIntermed()

Specified by:

getIntermed in interface org.apache.pig.Algebraic

getFinal

public String getFinal()

Specified by:

getFinal in interface org.apache.pig.Algebraic