org.apache.hadoop.mapred.lib
Class KeyFieldBasedComparator<K,V>
java.lang.Object
org.apache.hadoop.io.WritableComparator
org.apache.hadoop.mapreduce.lib.partition.KeyFieldBasedComparator<K,V>
org.apache.hadoop.mapred.lib.KeyFieldBasedComparator<K,V>
- All Implemented Interfaces:
- Comparator, Configurable, RawComparator, JobConfigurable
@InterfaceAudience.Public
@InterfaceStability.Stable
public class KeyFieldBasedComparator<K,V>
- extends KeyFieldBasedComparator<K,V>
- implements JobConfigurable
This comparator implementation provides a subset of the features provided
by the Unix/GNU Sort. In particular, the supported features are:
-n, (Sort numerically)
-r, (Reverse the result of comparison)
-k pos1[,pos2], where pos is of the form f[.c][opts], where f is the number
of the field to use, and c is the number of the first character from the
beginning of the field. Fields and character posns are numbered starting
with 1; a character position of zero in pos2 indicates the field's last
character. If '.c' is omitted from pos1, it defaults to 1 (the beginning
of the field); if omitted from pos2, it defaults to 0 (the end of the
field). opts are ordering options (any of 'nr' as described above).
We assume that the fields in the key are separated by
MRJobConfig.MAP_OUTPUT_KEY_FIELD_SEPERATOR
Methods inherited from class org.apache.hadoop.io.WritableComparator |
compare, compare, compareBytes, define, get, getKeyClass, hashBytes, hashBytes, newKey, readDouble, readFloat, readInt, readLong, readUnsignedShort, readVInt, readVLong |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
KeyFieldBasedComparator
public KeyFieldBasedComparator()
configure
public void configure(JobConf job)
- Description copied from interface:
JobConfigurable
- Initializes a new instance from a
JobConf
.
- Specified by:
configure
in interface JobConfigurable
- Parameters:
job
- the configuration
Copyright © 2014 Apache Software Foundation. All Rights Reserved.