simpledb.parallel

Class SingleFieldHashPartitionFunction

java.lang.Object

simpledb.parallel.PartitionFunction<java.lang.String,java.lang.String>

simpledb.parallel.SingleFieldHashPartitionFunction

All Implemented Interfaces:

java.io.Serializable

public class SingleFieldHashPartitionFunction
extends PartitionFunction<java.lang.String,java.lang.String>

The default implementation of the partition function. The partition of a tuple is decided by the hash code of a preset field of the tuple.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	FIELD_NAME
private java.lang.String	fieldName
private static long	serialVersionUID

Fields inherited from class simpledb.parallel.PartitionFunction

attributes, numPartition

Constructor Summary

Constructors

Constructor and Description
SingleFieldHashPartitionFunction(int numPartition)

Method Summary

Methods

Modifier and Type	Method and Description
int	partition(Tuple t, TupleDesc td) Given an input tuple t, determine which partition to route it to.
void	setAttribute(java.lang.String attribute, java.lang.String value) This partition function only needs the index of the partition field in deciding the tuple partitions

Methods inherited from class simpledb.parallel.PartitionFunction

getAttribute, numPartition

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

FIELD_NAME

public static final java.lang.String FIELD_NAME

See Also:

Constant Field Values

fieldName

private java.lang.String fieldName

Constructor Detail

SingleFieldHashPartitionFunction

public SingleFieldHashPartitionFunction(int numPartition)

Method Detail

setAttribute

public void setAttribute(java.lang.String attribute,
                java.lang.String value)

This partition function only needs the index of the partition field in deciding the tuple partitions

Overrides:

setAttribute in class PartitionFunction<java.lang.String,java.lang.String>

partition

public int partition(Tuple t,
            TupleDesc td)

Description copied from class: PartitionFunction

Given an input tuple t, determine which partition to route it to. Note: TupleDesc td is explicitly required even though the Tuple t includes a TupleDesc (obtained by calling t.getTupleDesc()) since field names might be absent from t.getTupleDesc(), and the PartitionFunction might require field names.

Specified by:

partition in class PartitionFunction<java.lang.String,java.lang.String>

Parameters:

t - the input tuple to route.

td - the tuple descriptor of the input tuple. Must have non-null names for those attributes that are used to compute the worker to route to.

Returns:

the worker to send the tuple to.