com.google.appengine.tools.mapreduce.inputs

Class DatastoreKeyInput

java.lang.Object

com.google.appengine.tools.mapreduce.Input<V>

com.google.appengine.tools.mapreduce.inputs.DatastoreKeyInput

All Implemented Interfaces:

Serializable

public final class DatastoreKeyInput
extends Input<V>

An input to read entity keys of a specified kind from the datastore.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
DatastoreKeyInput(com.google.appengine.api.datastore.Query query, int shardCount)
DatastoreKeyInput(String entityKind, int shardCount)
DatastoreKeyInput(String entityKind, int shardCount, String namespace)

Method Summary

Methods

Modifier and Type	Method and Description
protected DatastoreKeyInputReader	createReader(com.google.appengine.api.datastore.Query query)
List<InputReader<V>>	createReaders() Returns a list of readers for this input.
int	getShardCount()

Methods inherited from class com.google.appengine.tools.mapreduce.Input

getContext

Methods inherited from class java.lang.Object

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

Constructor Detail

DatastoreKeyInput

public DatastoreKeyInput(String entityKind,
                 int shardCount)

Parameters:

entityKind - entity kind to read from the datastore.

shardCount - number of parallel shards for the input.

DatastoreKeyInput

public DatastoreKeyInput(String entityKind,
                 int shardCount,
                 String namespace)

Parameters:

entityKind - entity kind to read from the datastore.

shardCount - the number of parallel shards to divide the input into.

namespace - the namespace of the entities (if null will use current).

DatastoreKeyInput

public DatastoreKeyInput(com.google.appengine.api.datastore.Query query,
                 int shardCount)

Parameters:

query - The query to map read from the datastore

shardCount - the number of parallel shards to divide the input into.

Method Detail

createReader

protected DatastoreKeyInputReader createReader(com.google.appengine.api.datastore.Query query)

createReaders

public List<InputReader<V>> createReaders()

Description copied from class: Input

Returns a list of readers for this input. It is the Input's responsibility to determine an appropriate number of readers to split into. This could be specified by the user or determined algorithmically. The number of input readers returned determines the number of map shards.

Specified by:

createReaders in class Input<V>

getShardCount

public int getShardCount()