org.apache.pig.impl.builtin

Class PoissonSampleLoader

java.lang.Object

org.apache.pig.LoadFunc

org.apache.pig.impl.builtin.SampleLoader

org.apache.pig.impl.builtin.PoissonSampleLoader

public class PoissonSampleLoader
extends SampleLoader

See "Skewed Join sampler" in http://wiki.apache.org/pig/PigSampler

Field Summary

Fields

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

Fields inherited from class org.apache.pig.impl.builtin.SampleLoader

loader, numSamples

Constructor Summary

Constructors

Constructor and Description
PoissonSampleLoader(java.lang.String funcSpec, java.lang.String ns)

Method Summary

Modifier and Type	Method and Description
Tuple	getNext() Retrieves the next tuple to be processed.
void	prepareToRead(org.apache.hadoop.mapreduce.RecordReader reader, PigSplit split) Initializes LoadFunc for reading data.

Methods inherited from class org.apache.pig.impl.builtin.SampleLoader

computeSamples, getInputFormat, getLoadCaster, getNumSamples, relativeToAbsolutePath, setLocation, setNumSamples, setUDFContextSignature, skipNext

Methods inherited from class org.apache.pig.LoadFunc

getAbsolutePath, getCacheFiles, getPathStrings, getShipFiles, join, warn

Methods inherited from class java.lang.Object

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

Field Detail

NUMROWS_TUPLE_MARKER

public static final java.lang.String NUMROWS_TUPLE_MARKER

See Also:

Constant Field Values

Constructor Detail

PoissonSampleLoader

public PoissonSampleLoader(java.lang.String funcSpec,
                           java.lang.String ns)

Method Detail

getNext

public Tuple getNext()
              throws java.io.IOException

Description copied from class: LoadFunc

Retrieves the next tuple to be processed. Implementations should NOT reuse tuple objects (or inner member objects) they return across calls and should return a different tuple object in each call.

Specified by:

getNext in class LoadFunc

Returns:

the next tuple to be processed or null if there are no more tuples to be processed.

Throws:

java.io.IOException - if there is an exception while retrieving the next tuple

prepareToRead

public void prepareToRead(org.apache.hadoop.mapreduce.RecordReader reader,
                          PigSplit split)
                   throws java.io.IOException

Description copied from class: LoadFunc

Initializes LoadFunc for reading data. This will be called during execution before any calls to getNext. The RecordReader needs to be passed here because it has been instantiated for a particular InputSplit.

Overrides:

prepareToRead in class SampleLoader

Parameters:

reader - RecordReader to be used by this instance of the LoadFunc

split - The input PigSplit to process

Throws:

java.io.IOException - if there is an exception during initialization