org.apache.pig.impl.io

Class PigNullableWritable

java.lang.Object

org.apache.pig.impl.io.PigNullableWritable

All Implemented Interfaces:

java.lang.Cloneable, java.lang.Comparable, org.apache.hadoop.io.Writable, org.apache.hadoop.io.WritableComparable

Direct Known Subclasses:

NullableBag, NullableBigDecimalWritable, NullableBigIntegerWritable, NullableBooleanWritable, NullableBytesWritable, NullableDateTimeWritable, NullableDoubleWritable, NullableFloatWritable, NullableIntWritable, NullableLongWritable, NullablePartitionWritable, NullableText, NullableTuple, NullableUnknownWritable

public abstract class PigNullableWritable
extends java.lang.Object
implements org.apache.hadoop.io.WritableComparable, java.lang.Cloneable

A base class for all types that pig uses to move data between map and reduce. It implements WritableComparable so that compareTo etc. can be called. It also wraps a WritableComparable 'value'. This is set by each different type to be an object of its specific type. It also provides a getIndex() and setIndex() calls that are used to get and set the index. These can be used by LocalRearrange, the partitioner, and Package to determine the index. Index and the null indicator are packed into one byte to save space.

Field Summary

Fields

Modifier and Type	Field and Description
static byte	idxSpace regular indices used in group and cogroup can only go from 0x00 to 0x7F
static byte	mqFlag indices in multiquery optimized maps will have the Most Significant Bit set This is a bitmask used in those cases.
protected org.apache.hadoop.io.WritableComparable	mValue

Constructor Summary

Constructors

Constructor and Description
PigNullableWritable()

Method Summary

Methods

Modifier and Type	Method and Description
PigNullableWritable	clone()
int	compareTo(java.lang.Object o) Compare two nullable objects.
boolean	equals(java.lang.Object arg0)
byte	getIndex()
abstract java.lang.Object	getValueAsPigType()
int	hashCode()
boolean	isNull()
void	readFields(java.io.DataInput in)
void	setIndex(byte index)
void	setNull(boolean isNull)
java.lang.String	toString()
void	write(java.io.DataOutput out)

Methods inherited from class java.lang.Object

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

Field Detail

mqFlag

public static final byte mqFlag

indices in multiquery optimized maps will have the Most Significant Bit set This is a bitmask used in those cases.

See Also:

Constant Field Values

idxSpace

public static final byte idxSpace

regular indices used in group and cogroup can only go from 0x00 to 0x7F

See Also:

Constant Field Values

mValue

protected org.apache.hadoop.io.WritableComparable mValue

Constructor Detail

PigNullableWritable

public PigNullableWritable()

Method Detail

clone

public PigNullableWritable clone()
                          throws java.lang.CloneNotSupportedException

Overrides:

clone in class java.lang.Object

Throws:

java.lang.CloneNotSupportedException

compareTo

public int compareTo(java.lang.Object o)

Compare two nullable objects. Step one is to check if either or both are null. If one is null and the other is not, then the one that is null is declared to be less. If both are null the indices are compared. If neither are null the indices are again compared. If these are equal, finally the values are compared. These comparators are used by hadoop as part of the post-map sort, when the data is still in object format.

Specified by:

compareTo in interface java.lang.Comparable

readFields

public void readFields(java.io.DataInput in)
                throws java.io.IOException

Specified by:

readFields in interface org.apache.hadoop.io.Writable

Throws:

java.io.IOException

write

public void write(java.io.DataOutput out)
           throws java.io.IOException

Specified by:

write in interface org.apache.hadoop.io.Writable

Throws:

java.io.IOException

isNull

public boolean isNull()

Returns:

the isNull

setNull

public void setNull(boolean isNull)

Parameters:

isNull - the isNull to set

getIndex

public byte getIndex()

Returns:

the index for this value

setIndex

public void setIndex(byte index)

Parameters:

index - for this value.

getValueAsPigType

public abstract java.lang.Object getValueAsPigType()

Returns:

The wrapped value as a pig type, not as a WritableComparable.

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object arg0)

Overrides:

equals in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object