cloud-fan commented on a change in pull request #32550: URL: https://github.com/apache/spark/pull/32550#discussion_r638789095
########## File path: sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/DynamicJoinSelection.scala ########## @@ -0,0 +1,82 @@ +/* + * 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.adaptive + +import org.apache.spark.sql.catalyst.optimizer.JoinSelectionHelper +import org.apache.spark.sql.catalyst.plans.logical.{HintInfo, Join, JoinStrategyHint, LogicalPlan, NO_BROADCAST_HASH, SHUFFLE_HASH} +import org.apache.spark.sql.catalyst.rules.Rule + +/** + * This optimization rule includes two join selection: + * 1. detects a join child that can not broadcast and every partition size less than local map + * threshold. Adds a shuffled_hash hint to force being shuffle hash join. + * 2. detects a join child that has a high ratio of empty partitions. + * Adds a no_broadcast_hash_join hint to avoid it being broadcast. + */ +object DynamicJoinSelection extends Rule[LogicalPlan] with JoinSelectionHelper { + + private def shouldDemoteBroadcastHashJoin(stage: ShuffleQueryStageExec): Boolean = { + val mapStats = stage.mapStats.get + val partitionCnt = mapStats.bytesByPartitionId.length + val nonZeroCnt = mapStats.bytesByPartitionId.count(_ > 0) + partitionCnt > 0 && nonZeroCnt > 0 && + (nonZeroCnt * 1.0 / partitionCnt) < conf.nonEmptyPartitionRatioForBroadcastJoin + } + + private def preferShuffledHashJoin(plan: LogicalPlan, stage: ShuffleQueryStageExec): Boolean = { + val localMapThreshold = conf.shuffleHashJoinLocalMapThreshold + !canBroadcastBySize(plan, conf) && Review comment: or we can have 3 hints for different cases 1. if we want to demote and want to use shuffle hash join, then use `SHUFFLE_HASH` hint 2. if we don't want to demote and want to use shuffle hash join, then use `PREFER_SHUFFLE_HASH` hint 3. if we want to demote and don't want to use shuffle hash join, then use `NO_BROADCAST_HASH` hint -- 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: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
