shark.execution.GroupByOperator.scala Maven / Gradle / Ivy
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/*
* Copyright (C) 2012 The Regents of The University California.
* All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package shark.execution
import org.apache.hadoop.hive.ql.exec.{GroupByOperator => HiveGroupByOperator}
import org.apache.hadoop.hive.ql.exec.{ReduceSinkOperator => HiveReduceSinkOperator}
/**
* Unlike Hive, group by in Shark is split into two different operators:
* GroupByPostShuffleOperator and GroupByPreShuffleOperator. The pre-shuffle one
* serves as a combiner on each map partition.
*
* These two classes are defined in org.apache.hadoop.hive.ql.exec package
* (scala files) to get around the problem that some Hive classes are only
* visibile within that class.
*/
object GroupByOperator {
def isPostShuffle(op: HiveGroupByOperator): Boolean = {
op.getParentOperators().get(0).isInstanceOf[HiveReduceSinkOperator]
}
}