org.apache.cassandra.hadoop
Class ColumnFamilyOutputFormat

java.lang.Object
  org.apache.hadoop.mapreduce.OutputFormat<java.nio.ByteBuffer,java.util.List<org.apache.cassandra.thrift.Mutation>>
      org.apache.cassandra.hadoop.ColumnFamilyOutputFormat

All Implemented Interfaces:

org.apache.hadoop.mapred.OutputFormat<java.nio.ByteBuffer,java.util.List<org.apache.cassandra.thrift.Mutation>>

public class ColumnFamilyOutputFormat
extends org.apache.hadoop.mapreduce.OutputFormat<java.nio.ByteBuffer,java.util.List<org.apache.cassandra.thrift.Mutation>>
implements org.apache.hadoop.mapred.OutputFormat<java.nio.ByteBuffer,java.util.List<org.apache.cassandra.thrift.Mutation>>

The ColumnFamilyOutputFormat acts as a Hadoop-specific OutputFormat that allows reduce tasks to store keys (and corresponding values) as Cassandra rows (and respective columns) in a given ColumnFamily.

As is the case with the ColumnFamilyInputFormat, you need to set the Keyspace and ColumnFamily in your Hadoop job Configuration. The ConfigHelper class, through its ConfigHelper.setOutputColumnFamily(org.apache.hadoop.conf.Configuration, java.lang.String, java.lang.String) method, is provided to make this simple.

For the sake of performance, this class employs a lazy write-back caching mechanism, where its record writer batches mutations created based on the reduce's inputs (in a task-specific map), and periodically makes the changes official by sending a batch mutate request to Cassandra.

Nested Class Summary

static class

ColumnFamilyOutputFormat.NullOutputCommitter An OutputCommitter that does nothing.

Field Summary

static java.lang.String	BATCH_THRESHOLD
static java.lang.String	QUEUE_SIZE

Constructor Summary

ColumnFamilyOutputFormat()

Method Summary

void	checkOutputSpecs(org.apache.hadoop.fs.FileSystem filesystem, org.apache.hadoop.mapred.JobConf job) Deprecated.
void	checkOutputSpecs(org.apache.hadoop.mapreduce.JobContext context) Check for validity of the output-specification for the job.
static org.apache.cassandra.thrift.Cassandra.Client	createAuthenticatedClient(org.apache.thrift.transport.TSocket socket, org.apache.hadoop.conf.Configuration conf) Return a client based on the given socket that points to the configured keyspace, and is logged in with the configured credentials.
org.apache.hadoop.mapreduce.OutputCommitter	getOutputCommitter(org.apache.hadoop.mapreduce.TaskAttemptContext context) The OutputCommitter for this format does not write any data to the DFS.
org.apache.cassandra.hadoop.ColumnFamilyRecordWriter	getRecordWriter(org.apache.hadoop.fs.FileSystem filesystem, org.apache.hadoop.mapred.JobConf job, java.lang.String name, org.apache.hadoop.util.Progressable progress) Deprecated.
org.apache.cassandra.hadoop.ColumnFamilyRecordWriter	getRecordWriter(org.apache.hadoop.mapreduce.TaskAttemptContext context) Get the RecordWriter for the given task.

Methods inherited from class java.lang.Object

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

Field Detail

BATCH_THRESHOLD

public static final java.lang.String BATCH_THRESHOLD

See Also:

Constant Field Values

QUEUE_SIZE

public static final java.lang.String QUEUE_SIZE

See Also:

Constant Field Values

Constructor Detail

ColumnFamilyOutputFormat

public ColumnFamilyOutputFormat()

Method Detail

checkOutputSpecs

public void checkOutputSpecs(org.apache.hadoop.mapreduce.JobContext context)

Check for validity of the output-specification for the job.

Specified by:

checkOutputSpecs in class org.apache.hadoop.mapreduce.OutputFormat<java.nio.ByteBuffer,java.util.List<org.apache.cassandra.thrift.Mutation>>

Parameters:

context - information about the job

Throws:

java.io.IOException - when output should not be attempted

getOutputCommitter

public org.apache.hadoop.mapreduce.OutputCommitter getOutputCommitter(org.apache.hadoop.mapreduce.TaskAttemptContext context)
                                                               throws java.io.IOException,
                                                                      java.lang.InterruptedException

The OutputCommitter for this format does not write any data to the DFS.

Specified by:

getOutputCommitter in class org.apache.hadoop.mapreduce.OutputFormat<java.nio.ByteBuffer,java.util.List<org.apache.cassandra.thrift.Mutation>>

Parameters:

context - the task context

Returns:

an output committer

Throws:

java.io.IOException

java.lang.InterruptedException

checkOutputSpecs

@Deprecated
public void checkOutputSpecs(org.apache.hadoop.fs.FileSystem filesystem,
                                        org.apache.hadoop.mapred.JobConf job)
                      throws java.io.IOException

Deprecated.

Fills the deprecated OutputFormat interface for streaming.

Specified by:

checkOutputSpecs in interface org.apache.hadoop.mapred.OutputFormat<java.nio.ByteBuffer,java.util.List<org.apache.cassandra.thrift.Mutation>>

Throws:

java.io.IOException

getRecordWriter

@Deprecated
public org.apache.cassandra.hadoop.ColumnFamilyRecordWriter getRecordWriter(org.apache.hadoop.fs.FileSystem filesystem,
                                                                                       org.apache.hadoop.mapred.JobConf job,
                                                                                       java.lang.String name,
                                                                                       org.apache.hadoop.util.Progressable progress)
                                                                     throws java.io.IOException

Deprecated.

Fills the deprecated OutputFormat interface for streaming.

Specified by:

getRecordWriter in interface org.apache.hadoop.mapred.OutputFormat<java.nio.ByteBuffer,java.util.List<org.apache.cassandra.thrift.Mutation>>

Throws:

java.io.IOException

getRecordWriter

public org.apache.cassandra.hadoop.ColumnFamilyRecordWriter getRecordWriter(org.apache.hadoop.mapreduce.TaskAttemptContext context)
                                                                     throws java.io.IOException,
                                                                            java.lang.InterruptedException

Get the RecordWriter for the given task.

Specified by:

getRecordWriter in class org.apache.hadoop.mapreduce.OutputFormat<java.nio.ByteBuffer,java.util.List<org.apache.cassandra.thrift.Mutation>>

Parameters:

context - the information about the current task.

Returns:

a RecordWriter to write the output for the job.

Throws:

java.io.IOException

java.lang.InterruptedException

createAuthenticatedClient

public static org.apache.cassandra.thrift.Cassandra.Client createAuthenticatedClient(org.apache.thrift.transport.TSocket socket,
                                                                                     org.apache.hadoop.conf.Configuration conf)
                                                                              throws org.apache.cassandra.thrift.InvalidRequestException,
                                                                                     org.apache.thrift.TException,
                                                                                     org.apache.cassandra.thrift.AuthenticationException,
                                                                                     org.apache.cassandra.thrift.AuthorizationException

Return a client based on the given socket that points to the configured keyspace, and is logged in with the configured credentials.

Parameters:

socket - a socket pointing to a particular node, seed or otherwise

conf - a job configuration

Returns:

a cassandra client

Throws:

org.apache.cassandra.thrift.InvalidRequestException

org.apache.thrift.TException

org.apache.cassandra.thrift.AuthenticationException

org.apache.cassandra.thrift.AuthorizationException