[GitHub] jerrychenhf commented on a change in pull request #20303: [SPARK-23128][SQL] A new approach to do adaptive execution in Spark SQL

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jerrychenhf commented on a change in pull request #20303: [SPARK-23128][SQL] A new approach to do adaptive execution in Spark SQL
URL: https://github.com/apache/spark/pull/20303#discussion_r252930149
 
 

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 File path: sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/QueryStage.scala
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+/*
+ * 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 scala.concurrent.Future
+
+import org.apache.spark.MapOutputStatistics
+import org.apache.spark.broadcast.Broadcast
+import org.apache.spark.rdd.RDD
+import org.apache.spark.sql.catalyst.InternalRow
+import org.apache.spark.sql.catalyst.expressions._
+import org.apache.spark.sql.catalyst.plans.physical.Partitioning
+import org.apache.spark.sql.execution._
+import org.apache.spark.sql.execution.exchange._
+
+/**
+ * In adaptive execution mode, an execution plan is divided into multiple QueryStages w.r.t. the
+ * exchange as boundary. Each QueryStage is a sub-tree that runs in a single Spark stage.
+ */
+abstract class QueryStage extends LeafExecNode {
 
 Review comment:
   Folks, I suggest we reconsider whether it is good to name it as "QueryStage".  For all Spark developers have the concept of Stage and used widely in Spark and UI, although there might not be such as class named "***Stage".  I know that adaptive execution does use Shuffle/Exchange as boundaries and divide the stages which is very close to the Spark "Stage" concept. But my question is whether this "QueryStage" class is used only in adaptive case, for example when adaptive execution is enabled, or this class is used as the same concept as Spark "Stage" even not under adaptive case.  if it is the former case, we should avoid the "QueryStage" name which may be very misleading with the exist Spark "Stage" concept and make the code hard to understand.
   
   For example, whether AdaptiveStage is a better name than "QueryState" to explicitly state the scope the stage concept is for.

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