cascading.scheme.hadoop

Class WritableSequenceFile

java.lang.Object

cascading.scheme.Scheme<Configuration,RecordReader,OutputCollector,java.lang.Object[],java.lang.Void>

cascading.scheme.hadoop.SequenceFile

cascading.scheme.hadoop.WritableSequenceFile

All Implemented Interfaces:

cascading.scheme.FileFormat, cascading.util.Traceable, java.io.Serializable

public class WritableSequenceFile
extends SequenceFile

Class WritableSequenceFile is a sub-class of SequenceFile that reads and writes values of the given writableType Class, instead of Tuple instances used by default in SequenceFile.

This Class is a convenience for those who need to read/write specific types from existing sequence files without them being wrapped in a Tuple instance.

Note due to the nature of sequence files, only one type can be stored in the key and value positions, they they can be uniquely different types (LongWritable, Text).

If keyType is null, valueType must not be null, and vice versa, assuming you only wish to store a single value.

NullWritable is used as the empty type for either a null keyType or valueType.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.Class<? extends Writable>	keyType
protected java.lang.Class<? extends Writable>	valueType

Constructor Summary

Constructors

Constructor and Description
WritableSequenceFile(cascading.tuple.Fields fields, java.lang.Class<? extends Writable> valueType) Constructor WritableSequenceFile creates a new WritableSequenceFile instance.
WritableSequenceFile(cascading.tuple.Fields fields, java.lang.Class<? extends Writable> keyType, java.lang.Class<? extends Writable> valueType) Constructor WritableSequenceFile creates a new WritableSequenceFile instance.

Method Summary

Modifier and Type	Method and Description
boolean	equals(java.lang.Object object)
int	hashCode()
void	sink(cascading.flow.FlowProcess<? extends Configuration> flowProcess, cascading.scheme.SinkCall<java.lang.Void,OutputCollector> sinkCall)
void	sinkConfInit(cascading.flow.FlowProcess<? extends Configuration> flowProcess, cascading.tap.Tap<Configuration,RecordReader,OutputCollector> tap, Configuration conf)
boolean	source(cascading.flow.FlowProcess<? extends Configuration> flowProcess, cascading.scheme.SourceCall<java.lang.Object[],RecordReader> sourceCall)

Methods inherited from class cascading.scheme.hadoop.SequenceFile

getExtension, sourceCleanup, sourceConfInit, sourcePrepare

Methods inherited from class cascading.scheme.Scheme

getNumSinkParts, getSinkFields, getSourceFields, getTrace, isSink, isSource, isSymmetrical, presentSinkFields, presentSinkFieldsInternal, presentSourceFields, presentSourceFieldsInternal, retrieveSinkFields, retrieveSourceFields, setNumSinkParts, setSinkFields, setSourceFields, sinkCleanup, sinkPrepare, sinkWrap, sourceRePrepare, sourceWrap, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

keyType

protected final java.lang.Class<? extends Writable> keyType

valueType

protected final java.lang.Class<? extends Writable> valueType

Constructor Detail

WritableSequenceFile

@ConstructorProperties(value={"fields","valueType"})
public WritableSequenceFile(cascading.tuple.Fields fields,
                                                                                 java.lang.Class<? extends Writable> valueType)

Constructor WritableSequenceFile creates a new WritableSequenceFile instance.

Parameters:

fields - of type Fields

valueType - of type Class, may not be null

WritableSequenceFile

@ConstructorProperties(value={"fields","keyType","valueType"})
public WritableSequenceFile(cascading.tuple.Fields fields,
                                                                                           java.lang.Class<? extends Writable> keyType,
                                                                                           java.lang.Class<? extends Writable> valueType)

Constructor WritableSequenceFile creates a new WritableSequenceFile instance.

Parameters:

fields - of type Fields

keyType - of type Class

valueType - of type Class

Method Detail

sinkConfInit

public void sinkConfInit(cascading.flow.FlowProcess<? extends Configuration> flowProcess,
                         cascading.tap.Tap<Configuration,RecordReader,OutputCollector> tap,
                         Configuration conf)

Overrides:

sinkConfInit in class SequenceFile

source

public boolean source(cascading.flow.FlowProcess<? extends Configuration> flowProcess,
                      cascading.scheme.SourceCall<java.lang.Object[],RecordReader> sourceCall)
               throws java.io.IOException

Overrides:

source in class SequenceFile

Throws:

java.io.IOException

sink

public void sink(cascading.flow.FlowProcess<? extends Configuration> flowProcess,
                 cascading.scheme.SinkCall<java.lang.Void,OutputCollector> sinkCall)
          throws java.io.IOException

Overrides:

sink in class SequenceFile

Throws:

java.io.IOException

equals

public boolean equals(java.lang.Object object)

Overrides:

equals in class cascading.scheme.Scheme<Configuration,RecordReader,OutputCollector,java.lang.Object[],java.lang.Void>

hashCode

public int hashCode()

Overrides:

hashCode in class cascading.scheme.Scheme<Configuration,RecordReader,OutputCollector,java.lang.Object[],java.lang.Void>