HeartSaVioR commented on a change in pull request #31986: URL: https://github.com/apache/spark/pull/31986#discussion_r629830829
########## File path: sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/UpdatingSessionsExec.scala ########## @@ -0,0 +1,77 @@ +/* + * 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.aggregate + +import org.apache.spark.rdd.RDD +import org.apache.spark.sql.catalyst.InternalRow +import org.apache.spark.sql.catalyst.expressions.{Ascending, Attribute, SortOrder} +import org.apache.spark.sql.catalyst.plans.physical.{AllTuples, ClusteredDistribution, Distribution, Partitioning} +import org.apache.spark.sql.execution.{SparkPlan, UnaryExecNode} + +/** + * This node updates the session window spec of each input rows via analyzing neighbor rows and + * determining rows belong to the same session window. The number of input rows remains the same. + * This node requires sort on input rows by group keys + the start time of session window. + * + * There are lots of overhead compared to [[MergingSessionsExec]]. Use [[MergingSessionsExec]] + * instead whenever possible. Use this node only when we cannot apply both calculations + * determining session windows and aggregating rows in session window altogether. + * + * Refer [[UpdatingSessionsIterator]] for more details. + */ +case class UpdatingSessionsExec( + keyExpressions: Seq[Attribute], + sessionExpression: Attribute, + child: SparkPlan) extends UnaryExecNode { + + private val groupingWithoutSessionExpression = keyExpressions.filterNot { + p => p.semanticEquals(sessionExpression) + } + private val groupingWithoutSessionAttributes = + groupingWithoutSessionExpression.map(_.toAttribute) + + override protected def doExecute(): RDD[InternalRow] = { + val inMemoryThreshold = sqlContext.conf.sessionWindowBufferInMemoryThreshold + val spillThreshold = sqlContext.conf.sessionWindowBufferSpillThreshold + + child.execute().mapPartitions { iter => + new UpdatingSessionsIterator(iter, keyExpressions, sessionExpression, + child.output, inMemoryThreshold, spillThreshold) + } + } + + override def output: Seq[Attribute] = child.output + + override def outputPartitioning: Partitioning = child.outputPartitioning + + override def requiredChildDistribution: Seq[Distribution] = { + if (groupingWithoutSessionExpression.isEmpty) { + AllTuples :: Nil + } else { + ClusteredDistribution(groupingWithoutSessionExpression) :: Nil + } + } + + override def requiredChildOrdering: Seq[Seq[SortOrder]] = { + Seq((groupingWithoutSessionAttributes ++ Seq(sessionExpression)) Review comment: Ah I remembered the reason. You can't safely assume session expression is placed at the end of grouping. Let me revert back. -- 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
