org.apache.cassandra.hadoop.cql3

Class CqlOutputFormat

java.lang.Object

org.apache.hadoop.mapreduce.OutputFormat<java.util.Map<java.lang.String,java.nio.ByteBuffer>,java.util.List<java.nio.ByteBuffer>>

org.apache.cassandra.hadoop.cql3.CqlOutputFormat

All Implemented Interfaces:

org.apache.hadoop.mapred.OutputFormat<java.util.Map<java.lang.String,java.nio.ByteBuffer>,java.util.List<java.nio.ByteBuffer>>

public class CqlOutputFormat
extends org.apache.hadoop.mapreduce.OutputFormat<java.util.Map<java.lang.String,java.nio.ByteBuffer>,java.util.List<java.nio.ByteBuffer>>
implements org.apache.hadoop.mapred.OutputFormat<java.util.Map<java.lang.String,java.nio.ByteBuffer>,java.util.List<java.nio.ByteBuffer>>

The CqlOutputFormat acts as a Hadoop-specific OutputFormat that allows reduce tasks to store keys (and corresponding bound variable values) as CQL rows (and respective columns) in a given table.

As is the case with the org.apache.cassandra.hadoop.ColumnFamilyInputFormat, you need to set the prepared statement in your Hadoop job Configuration. The CqlConfigHelper class, through its CqlConfigHelper.setOutputCql(org.apache.hadoop.conf.Configuration, java.lang.String) method, is provided to make this simple. you need to set the Keyspace. The ConfigHelper class, through its ConfigHelper.setOutputColumnFamily(org.apache.hadoop.conf.Configuration, 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 prepared statement binded variable values created based on the reduce's inputs (in a task-specific map), and periodically makes the changes official by sending a execution of prepared statement request to Cassandra.

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	BATCH_THRESHOLD
static java.lang.String	QUEUE_SIZE

Constructor Summary

Constructors

Constructor and Description
CqlOutputFormat()

Method Summary

Modifier and Type	Method and Description
protected void	checkOutputSpecs(org.apache.hadoop.conf.Configuration conf)
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.
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.cql3.CqlRecordWriter	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.cql3.CqlRecordWriter	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

CqlOutputFormat

public CqlOutputFormat()

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.util.Map<java.lang.String,java.nio.ByteBuffer>,java.util.List<java.nio.ByteBuffer>>

Parameters:

context - information about the job

checkOutputSpecs

protected void checkOutputSpecs(org.apache.hadoop.conf.Configuration conf)

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.util.Map<java.lang.String,java.nio.ByteBuffer>,java.util.List<java.nio.ByteBuffer>>

Throws:

java.io.IOException

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.util.Map<java.lang.String,java.nio.ByteBuffer>,java.util.List<java.nio.ByteBuffer>>

Parameters:

context - the task context

Returns:

an output committer

Throws:

java.io.IOException

java.lang.InterruptedException

getRecordWriter

@Deprecated
public org.apache.cassandra.hadoop.cql3.CqlRecordWriter 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.util.Map<java.lang.String,java.nio.ByteBuffer>,java.util.List<java.nio.ByteBuffer>>

Throws:

java.io.IOException

getRecordWriter

public org.apache.cassandra.hadoop.cql3.CqlRecordWriter 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.util.Map<java.lang.String,java.nio.ByteBuffer>,java.util.List<java.nio.ByteBuffer>>

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