com.mongodb

Class MapReduceOutput

java.lang.Object

com.mongodb.MapReduceOutput

public class MapReduceOutput
extends Object

Represents the result of a map/reduce operation. Users should interact with the results of the map reduce via the results() method, or by interacting directly with the collection the results were input into.

There will be substantial changes to this class in the 3.x release, please check the deprecation tags for the methods that will be removed.

MongoDB documentation

Map Reduce Command

Constructor Summary

Constructors

Constructor and Description
MapReduceOutput(DBCollection from, DBObject cmd, CommandResult raw) Deprecated. In the 3.0 version of the driver, this will be constructed only by the driver, and will therefore not have a public constructor.

Method Summary

Methods

Modifier and Type	Method and Description
void	drop() Drops the collection that holds the results.
String	getCollectionName() Get the name of the collection that the results of the map reduce were saved into.
DBObject	getCommand() Get the original command that was sent to the database.
CommandResult	getCommandResult() Deprecated. It is not recommended to access the command result returned by the server as the format can change between releases. This has been replaced with a series of specific getters for the values on the CommandResult (getCollectionName, getDatabaseName, getDuration, getEmitCount, getOutputCount, getInputCount). The method results() will continue to return an Iterable<DBObjects>, that should be used to obtain the results of the map-reduce. This method will be removed in 3.0.
String	getDatabaseName() Get the name of the database that the results of the map reduce were saved into.
int	getDuration() Get the amount of time, in milliseconds, that it took to run this map reduce.
int	getEmitCount() Get the number of messages emitted from the provided map function.
int	getInputCount() Get the number of documents that were input into the map reduce operation
DBCollection	getOutputCollection() Gets the collection that holds the results (Will return null if results are Inline).
int	getOutputCount() Get the number of documents generated as a result of this map reduce
BasicDBObject	getRaw() Deprecated. It is not recommended to access the raw document returned by the server as the format can change between releases. This has been replaced with a series of specific getters for the values on the result (getCollectionName, getDatabaseName, getDuration, getEmitCount, getOutputCount, getInputCount). The method results() will continue to return an Iterable<DBObjects>, that should be used to obtain the results of the map-reduce. This method will be removed in 3.0.
ServerAddress	getServerUsed() Get the server that the map reduce command was run on.
Iterable<DBObject>	results() Returns an iterable containing the results of the operation.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

MapReduceOutput

@Deprecated
public MapReduceOutput(DBCollection from,
                          DBObject cmd,
                          CommandResult raw)

Deprecated. In the 3.0 version of the driver, this will be constructed only by the driver, and will therefore not have a public constructor.

Creates a new MapReduceOutput.

Parameters:

from - the DBCollection the Map Reduce was run against

cmd - the original Map Reduce command as a DBObject

raw - the CommandResult containing the raw response from the server.

Method Detail

results

public Iterable<DBObject> results()

Returns an iterable containing the results of the operation.

Returns:

the results in iterable form

drop

public void drop()

Drops the collection that holds the results. Does nothing if the map-reduce returned the results inline.

Throws:

MongoException

getOutputCollection

public DBCollection getOutputCollection()

Gets the collection that holds the results (Will return null if results are Inline).

Returns:

the collection or null

getRaw

@Deprecated
public BasicDBObject getRaw()

Deprecated. It is not recommended to access the raw document returned by the server as the format can change between releases. This has been replaced with a series of specific getters for the values on the result (getCollectionName, getDatabaseName, getDuration, getEmitCount, getOutputCount, getInputCount). The method results() will continue to return an Iterable<DBObjects>, that should be used to obtain the results of the map-reduce. This method will be removed in 3.0.

Get the full document containing the raw results returned by the server.

Returns:

The result of the map-reduce operation as a document

getCommandResult

@Deprecated
public CommandResult getCommandResult()

Deprecated. It is not recommended to access the command result returned by the server as the format can change between releases. This has been replaced with a series of specific getters for the values on the CommandResult (getCollectionName, getDatabaseName, getDuration, getEmitCount, getOutputCount, getInputCount). The method results() will continue to return an Iterable<DBObjects>, that should be used to obtain the results of the map-reduce. This method will be removed in 3.0.

The CommandResult should not be used directly at all, this will be removed.

Returns:

a CommandResult representing the output of the map-reduce in its raw form from the server.

getCommand

public DBObject getCommand()

Get the original command that was sent to the database.

Returns:

a DBObject containing the values of the original map-reduce command.

getServerUsed

public ServerAddress getServerUsed()

Get the server that the map reduce command was run on.

Returns:

a ServerAddress of the server that the command ran against.

toString

public String toString()

Overrides:

toString in class Object

getCollectionName

public final String getCollectionName()

Get the name of the collection that the results of the map reduce were saved into. If the map reduce was an inline operation (i.e . the results were returned directly from calling the map reduce) this will return null.

Returns:

the name of the collection that the map reduce results are stored in

getDatabaseName

public String getDatabaseName()

Get the name of the database that the results of the map reduce were saved into. If the map reduce was an inline operation (i.e . the results were returned directly from calling the map reduce) this will return null.

Returns:

the name of the database that holds the collection that the map reduce results are stored in

getDuration

public int getDuration()

Get the amount of time, in milliseconds, that it took to run this map reduce.

Returns:

an int representing the number of milliseconds it took to run the map reduce operation

getInputCount

public int getInputCount()

Get the number of documents that were input into the map reduce operation

Returns:

the number of documents that read while processing this map reduce

getOutputCount

public int getOutputCount()

Get the number of documents generated as a result of this map reduce

Returns:

the number of documents output by the map reduce

getEmitCount

public int getEmitCount()

Get the number of messages emitted from the provided map function.

Returns:

the number of items emitted from the map function