[GitHub] [spark] ulysses-you commented on a change in pull request #32391: [SPARK-35264][SQL] Support AQE side broadcastJoin threshold

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ulysses-you commented on a change in pull request #32391:
URL: https://github.com/apache/spark/pull/32391#discussion_r622892555



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File path: sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/DynamicJoinSelection.scala
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@@ -0,0 +1,87 @@
+/*
+ * 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.{BuildLeft, BuildRight, JoinSelectionHelper}
+import org.apache.spark.sql.catalyst.planning.ExtractEquiJoinKeys
+import org.apache.spark.sql.catalyst.plans.JoinType
+import org.apache.spark.sql.catalyst.plans.logical.{BROADCAST, HintInfo, JoinHint, LogicalPlan, NO_BROADCAST_HASH, SHUFFLE_HASH}
+import org.apache.spark.sql.catalyst.rules.Rule
+
+/**
+ * The main idea here is that make join config isolation between normal planner and aqe planner
+ * which shared the same code path.
+ * In order to achieve this we use a specific join hint in advance during AQE framework and then
+ * at JoinSelection side it will take and follow the inserted hint.
+ *
+ * For now we only support select strategy for equi join, and follow this order:
+ *   1. mark join as broadcast hash join if possible
+ *   2. mark join as shuffled hash join if possible
+ *
+ * Note that, we don't override join strategy if user specifies a join hint.
+ */
+object DynamicJoinSelection extends Rule[LogicalPlan] with JoinSelectionHelper {
+  final override val isAdaptive: Boolean = true
+
+  private def insertJoinHint(

Review comment:
       @cloud-fan  That might work but I want to explain some reason of adding this rule at AQE optimizer side. Currently it looks like we follow the `JoinSelection` logic but it may be broken. Then we can easily add other join selection in future.
   
   Let's assume if we have an another config like `spark.sql.adaptive.shuffledHashJoinBuildSideThreshold`, then we can add the check in this rule so that we can pick the SMJ instead of SHJ if it's partition size over the threshold.




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