sarutak commented on a change in pull request #29677: URL: https://github.com/apache/spark/pull/29677#discussion_r499999653
########## File path: sql/core/src/main/scala/org/apache/spark/sql/execution/exchange/PruneShuffle.scala ########## @@ -0,0 +1,43 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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 org.apache.spark.sql.execution.exchange + +import org.apache.spark.sql.catalyst.rules.Rule +import org.apache.spark.sql.execution.SparkPlan + +/** + * Removes unnecessary shuffles. A shuffle can be introduced by [[Rule]]s for + * [[SparkPlan]]s, such as [[EnsureRequirements]] and then, its immediate child of + * another shuffle should be unnecessary. + */ +case class PruneShuffle() extends Rule[SparkPlan] { + + override def apply(plan: SparkPlan): SparkPlan = plan.transform { + case op @ ShuffleExchangeExec(_, child: ShuffleExchangeExec, _) => + op.withNewChildren(Seq(pruneShuffle(child))) + case other => other + } + + private def pruneShuffle(plan: SparkPlan): SparkPlan = { + plan match { + case shuffle: ShuffleExchangeExec => + pruneShuffle(shuffle.child) + case other => other + } + } +} Review comment: Similar to what is discussed [here](https://github.com/apache/spark/pull/21072#discussion_r183392394), I'd like to avoid unnecessary transformation. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
