org.apache.datasketches.pig.hash

Class MurmurHash3

java.lang.Object

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

org.apache.datasketches.pig.hash.MurmurHash3

public class MurmurHash3
extends org.apache.pig.EvalFunc<org.apache.pig.data.Tuple>

Computes a 128-bit MurmurHash3 hash of data input types: String, DataByteArray, Long, Integer, Double, and Float. The 2nd optional parameter can be a Long or Integer seed. The 3rd optional parameter can be a positive Integer modulus divisor. If the divisor is provided, the Integer modulus remainder is computed on the entire 128-bit hash output treated as if it were a 128-bit positive value.

Nested Class Summary

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
MurmurHash3()

Method Summary

Modifier and Type	Method and Description
org.apache.pig.data.Tuple	exec(org.apache.pig.data.Tuple input) Top Level Exec Function.
org.apache.pig.impl.logicalLayer.schema.Schema	outputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input) The output consists of two longs, or 128 bits, plus the result of the modulo division if specified.

Methods inherited from class org.apache.pig.EvalFunc

allowCompileTimeCalculation, finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLoadCaster, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, getSchemaType, getShipFiles, isAsynchronous, needEndOfAllInputProcessing, 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

MurmurHash3

public MurmurHash3()

Method Detail

exec

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

Top Level Exec Function.

This method accepts an object to be hashed and returns a Hash Result Tuple.

Hash Input Tuple

• Tuple: TUPLE (Must contain 1 field and may contain 2 or 3):
  
  • index 0: Object to be hashed: one of String, DataByteArray, Long, Integer, Double, Float.
  • index 1: Seed: Long or Integer
  • index 2: Modulus divisor: Integer; must be positive.

Any other input tuple will throw an exception!

Hash Result Tuple

• Tuple: TUPLE (Contains 3 fields)
  • index 0: Long: LONG: The 1st 64 bits of the hash.
  • index 1: Long: LONG: The 2nd 64 bits of the hash.
  • index 2: Integer: INTEGER: Result of modulo operation, -1 if not computed.

Specified by:

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

Parameters:

input - Hash Input Tuple. If null or empty exec returns null.

Throws:

IOException

outputSchema

public org.apache.pig.impl.logicalLayer.schema.Schema outputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input)

The output consists of two longs, or 128 bits, plus the result of the modulo division if specified.

Overrides:

outputSchema in class org.apache.pig.EvalFunc<org.apache.pig.data.Tuple>