org.apache.cassandra.hadoop.cql3

Class CqlInputFormat

java.lang.Object

org.apache.hadoop.mapreduce.InputFormat<Long,com.datastax.driver.core.Row>

org.apache.cassandra.hadoop.cql3.CqlInputFormat

All Implemented Interfaces:

org.apache.hadoop.mapred.InputFormat<Long,com.datastax.driver.core.Row>

public class CqlInputFormat
extends org.apache.hadoop.mapreduce.InputFormat<Long,com.datastax.driver.core.Row>
implements org.apache.hadoop.mapred.InputFormat<Long,com.datastax.driver.core.Row>

Hadoop InputFormat allowing map/reduce against Cassandra rows within one ColumnFamily. At minimum, you need to set the KS and CF in your Hadoop job Configuration. The ConfigHelper class is provided to make this simple: ConfigHelper.setInputColumnFamily You can also configure the number of rows per InputSplit with 1: ConfigHelper.setInputSplitSize. The default split size is 64k rows. or 2: ConfigHelper.setInputSplitSizeInMb. InputSplit size in MB with new, more precise method If no value is provided for InputSplitSizeInMb, we default to using InputSplitSize. CQLConfigHelper.setInputCQLPageRowSize. The default page row size is 1000. You should set it to "as big as possible, but no bigger." It set the LIMIT for the CQL query, so you need set it big enough to minimize the network overhead, and also not too big to avoid out of memory issue. other native protocol connection parameters in CqlConfigHelper

Field Summary

Fields

Modifier and Type	Field and Description
static String	MAPRED_TASK_ID

Constructor Summary

Constructors

Constructor and Description
CqlInputFormat()

Method Summary

Modifier and Type	Method and Description
org.apache.hadoop.mapreduce.RecordReader<Long,com.datastax.driver.core.Row>	createRecordReader(org.apache.hadoop.mapreduce.InputSplit arg0, org.apache.hadoop.mapreduce.TaskAttemptContext arg1)
org.apache.hadoop.mapred.RecordReader<Long,com.datastax.driver.core.Row>	getRecordReader(org.apache.hadoop.mapred.InputSplit split, org.apache.hadoop.mapred.JobConf jobConf, org.apache.hadoop.mapred.Reporter reporter)
org.apache.hadoop.mapred.InputSplit[]	getSplits(org.apache.hadoop.mapred.JobConf jobConf, int numSplits)
List<org.apache.hadoop.mapreduce.InputSplit>	getSplits(org.apache.hadoop.mapreduce.JobContext context)
protected void	validateConfiguration(org.apache.hadoop.conf.Configuration conf)

Methods inherited from class java.lang.Object

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

Field Detail

MAPRED_TASK_ID

public static final String MAPRED_TASK_ID

See Also:

Constant Field Values

Constructor Detail

CqlInputFormat

public CqlInputFormat()

Method Detail

getRecordReader

public org.apache.hadoop.mapred.RecordReader<Long,com.datastax.driver.core.Row> getRecordReader(org.apache.hadoop.mapred.InputSplit split,
                                                                                                org.apache.hadoop.mapred.JobConf jobConf,
                                                                                                org.apache.hadoop.mapred.Reporter reporter)
                                                                                         throws IOException

Specified by:

getRecordReader in interface org.apache.hadoop.mapred.InputFormat<Long,com.datastax.driver.core.Row>

Throws:

IOException

createRecordReader

public org.apache.hadoop.mapreduce.RecordReader<Long,com.datastax.driver.core.Row> createRecordReader(org.apache.hadoop.mapreduce.InputSplit arg0,
                                                                                                      org.apache.hadoop.mapreduce.TaskAttemptContext arg1)

Specified by:

createRecordReader in class org.apache.hadoop.mapreduce.InputFormat<Long,com.datastax.driver.core.Row>

validateConfiguration

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

getSplits

public List<org.apache.hadoop.mapreduce.InputSplit> getSplits(org.apache.hadoop.mapreduce.JobContext context)
                                                       throws IOException

Specified by:

getSplits in class org.apache.hadoop.mapreduce.InputFormat<Long,com.datastax.driver.core.Row>

Throws:

IOException

getSplits

public org.apache.hadoop.mapred.InputSplit[] getSplits(org.apache.hadoop.mapred.JobConf jobConf,
                                                       int numSplits)
                                                throws IOException

Specified by:

getSplits in interface org.apache.hadoop.mapred.InputFormat<Long,com.datastax.driver.core.Row>

Throws:

IOException