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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>
@InterfaceAudience.Public @InterfaceStability.Stable public class KeyFieldBasedComparator<K,V>
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
Field Summary |
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Fields inherited from class org.apache.hadoop.mapreduce.lib.partition.KeyFieldBasedComparator |
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COMPARATOR_OPTIONS |
Constructor Summary | |
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KeyFieldBasedComparator()
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Method Summary | |
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void |
configure(JobConf job)
Initializes a new instance from a JobConf . |
Methods inherited from class org.apache.hadoop.mapreduce.lib.partition.KeyFieldBasedComparator |
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compare, getConf, getKeyFieldComparatorOption, setConf, setKeyFieldComparatorOptions |
Methods inherited from class org.apache.hadoop.io.WritableComparator |
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compare, compare, compareBytes, define, get, getKeyClass, hashBytes, hashBytes, newKey, readDouble, readFloat, readInt, readLong, readUnsignedShort, readVInt, readVLong |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Methods inherited from interface java.util.Comparator |
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equals |
Constructor Detail |
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public KeyFieldBasedComparator()
Method Detail |
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public void configure(JobConf job)
JobConfigurable
JobConf
.
configure
in interface JobConfigurable
job
- the configuration
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