MapReduce.MapEmitter<K,V>, MapReduce.NullObject, MapReduce.ReduceEmitter<OK,OV>, MapReduce.StageMAP_REDUCE| Constructor and Description |
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MapReduceBB() |
| Modifier and Type | Method and Description |
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boolean |
doStage(MapReduce.Stage stage)
A MapReduce job can be map-only, map-reduce-only, or map-combine-reduce.
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List<Integer> |
generateFinalResult(Iterator<KeyValue<Integer,Integer>> keyValues)
The key/value pairs emitted by reduce() (or map() in a map-only job) can be iterated to generate a local JVM Java object.
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Optional<Comparator<Integer>> |
getMapKeySort()
If a
Comparator is provided, then all pairs leaving the MapReduce.MapEmitter are sorted. |
String |
getMemoryKey()
The results of the MapReduce job are associated with a memory-key to ultimately be stored in
Memory. |
void |
map(Vertex vertex,
MapReduce.MapEmitter<Integer,Integer> emitter)
The map() method is logically executed at all vertices in the graph in parallel.
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clone, equals, hashCode, storeState, toStringfinalize, getClass, notify, notifyAll, wait, wait, waitaddResultToMemory, combine, createMapReduce, getReduceKeySort, loadState, reduce, workerEnd, workerStartpublic boolean doStage(MapReduce.Stage stage)
MapReducestage - the stage to check for definition.public void map(Vertex vertex, MapReduce.MapEmitter<Integer,Integer> emitter)
MapReduceMapReduce classes must at least provide an implementation of MapReduce#map(Vertex, MapEmitter).vertex - the current vertex being map() processed.emitter - the component that allows for key/value pairs to be emitted to the next stage.public Optional<Comparator<Integer>> getMapKeySort()
MapReduceComparator is provided, then all pairs leaving the MapReduce.MapEmitter are sorted.
The sorted results are either fed sorted to the combine/reduce-stage or as the final output.
If sorting is not required, then Optional.empty() should be returned as sorting is computationally expensive.
The default implementation returns Optional.empty().Optional of a comparator for sorting the map output.public String getMemoryKey()
MapReduceMemory.public List<Integer> generateFinalResult(Iterator<KeyValue<Integer,Integer>> keyValues)
MapReducekeyValues - the key/value pairs that were emitted from reduce() (or map() in a map-only job)Copyright © 2013–2021 Apache Software Foundation. All rights reserved.