@InterfaceAudience.Public @InterfaceStability.Stable public interface ValueAggregatorDescriptor
Configurationobject. Its main function is to generate a list of aggregation-id/value pairs. An aggregation id encodes an aggregation type which is used to guide the way to aggregate the value in the reduce/combiner phrase of an Aggregate based job. The mapper in an Aggregate based map/reduce job may create one or more of ValueAggregatorDescriptor objects at configuration time. For each input key/value pair, the mapper will use those objects to create aggregation id/value pairs.
|Modifier and Type||Field and Description|
static final Text ONE
key- input key
val- input value
void configure(Configuration conf)
conf- a Configuration object that may contain the information that can be used to configure the object.
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