public FaunusPipeline groupCount ( final String keyClosure , final String valueClosure ) { this . state . assertNotLocked ( ) ; this . compiler . addMapReduce ( GroupCountMapReduce . Map . class , GroupCountMapReduce . Combiner . class , GroupCountMapReduce . Reduce . class , Text . class , LongWritable . class , Text . class , LongWritable . class , GroupCountMapReduce . createConfiguration ( this . state . getElementType ( ) , this . validateClosure ( keyClosure ) , this . validateClosure ( valueClosure ) ) ) ; makeMapReduceString ( GroupCountMapReduce . class ) ; return this ; }
Apply the provided closure to the incoming element to determine the grouping key . Then apply the value closure to the current element to determine the count increment . The results are stored in the jobs sideeffect file in HDFS .