org.apache.hadoop.hive.ql.exec.mr
Class ExecReducer
java.lang.Object
MapReduceBase
org.apache.hadoop.hive.ql.exec.mr.ExecReducer
public class ExecReducer
- extends MapReduceBase
ExecReducer is the generic Reducer class for Hive. Together with ExecMapper it is
the bridge between the map-reduce framework and the Hive operator pipeline at
execution time. It's main responsabilities are:
- Load and setup the operator pipeline from XML
- Run the pipeline by transforming key, value pairs to records and forwarding them to the operators
- Sending start and end group messages to separate records with same key from one another
- Catch and handle errors during execution of the operators.
Field Summary |
static org.apache.commons.logging.Log |
l4j
|
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
l4j
public static final org.apache.commons.logging.Log l4j
ExecReducer
public ExecReducer()
configure
public void configure(JobConf job)
reduce
public void reduce(Object key,
Iterator values,
OutputCollector output,
Reporter reporter)
throws IOException
- Throws:
IOException
close
public void close()
Copyright © 2012 The Apache Software Foundation