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121 changes: 121 additions & 0 deletions
121
spark/src/main/scala/org/apache/comet/CometCostEvaluator.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. | ||
| */ | ||
|
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| package org.apache.comet | ||
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| import org.apache.spark.internal.Logging | ||
| import org.apache.spark.sql.comet.{CometExec, CometPlan, CometRowToColumnarExec, CometSinkPlaceHolder} | ||
| import org.apache.spark.sql.execution.{ColumnarToRowExec, InputAdapter, RowToColumnarExec, SparkPlan, WholeStageCodegenExec} | ||
| import org.apache.spark.sql.execution.adaptive.{AdaptiveSparkPlanExec, Cost, CostEvaluator, QueryStageExec, SimpleCost} | ||
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| /** | ||
| * The goal of this cost model is to avoid introducing performance regressions in query stages | ||
| * during AQE. | ||
| * | ||
| * This evaluator will be called twice; once for the original Spark plan and once for the Comet | ||
| * plan. Spark will choose the cheapest plan. | ||
| */ | ||
| class CometCostEvaluator extends CostEvaluator with Logging { | ||
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| /** Baseline cost for Spark operator is 1.0 */ | ||
| val DEFAULT_SPARK_OPERATOR_COST = 1.0 | ||
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| /** Relative cost of Comet operator */ | ||
| val DEFAULT_COMET_OPERATOR_COST = 0.8 | ||
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| /** Relative cost of a transition (C2R, R2C) */ | ||
| val DEFAULT_TRANSITION_COST = 1.0 | ||
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| override def evaluateCost(plan: SparkPlan): Cost = { | ||
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| // TODO this is a crude prototype where we just penalize transitions, but | ||
| // this can evolve into a true cost model where we have real numbers for the relative | ||
| // performance of Comet operators & expressions versus the Spark versions | ||
| // | ||
| // Some areas to explore | ||
| // - can we use statistics from previous query stage(s)? | ||
| // - transition after filter should be cheaper than transition before filter (such as when | ||
| // reading from Parquet followed by filter. Comet will filter first then transition) | ||
| def computePlanCost(plan: SparkPlan): Double = { | ||
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| // get children even for leaf nodes at query stage edges | ||
| def getChildren(plan: SparkPlan) = plan match { | ||
| case a: AdaptiveSparkPlanExec => Seq(a.inputPlan) | ||
| case qs: QueryStageExec => Seq(qs.plan) | ||
| case p => p.children | ||
| } | ||
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| val children = getChildren(plan) | ||
| val childPlanCost = children.map(computePlanCost).sum | ||
| val operatorCost = plan match { | ||
| case _: AdaptiveSparkPlanExec => 0 | ||
| case _: CometSinkPlaceHolder => 0 | ||
| case _: InputAdapter => 0 | ||
| case _: WholeStageCodegenExec => 0 | ||
| case RowToColumnarExec(_) => DEFAULT_TRANSITION_COST | ||
| case ColumnarToRowExec(_) => DEFAULT_TRANSITION_COST | ||
| case CometRowToColumnarExec(_) => DEFAULT_TRANSITION_COST | ||
| case _: CometExec => DEFAULT_COMET_OPERATOR_COST | ||
| case _ => DEFAULT_SPARK_OPERATOR_COST | ||
| } | ||
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| def isSparkNative(plan: SparkPlan): Boolean = plan match { | ||
| case p: AdaptiveSparkPlanExec => isSparkNative(p.inputPlan) | ||
| case p: QueryStageExec => isSparkNative(p.plan) | ||
| case _: CometPlan => false | ||
| case _ => true | ||
| } | ||
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| def isCometNative(plan: SparkPlan): Boolean = plan match { | ||
| case p: AdaptiveSparkPlanExec => isCometNative(p.inputPlan) | ||
| case p: QueryStageExec => isCometNative(p.plan) | ||
| case _: CometPlan => true | ||
| case _ => false | ||
| } | ||
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| def isTransition(plan1: SparkPlan, plan2: SparkPlan) = { | ||
| (isSparkNative(plan1) && isCometNative(plan2)) || | ||
| (isCometNative(plan1) && isSparkNative(plan2)) | ||
| } | ||
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| val transitionCost = if (children.exists(ch => isTransition(plan, ch))) { | ||
| DEFAULT_TRANSITION_COST | ||
| } else { | ||
| 0 | ||
| } | ||
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| val totalCost = operatorCost + transitionCost + childPlanCost | ||
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| logWarning(s"total cost is $totalCost ($operatorCost + $transitionCost + $childPlanCost) " + | ||
| s"for ${plan.nodeName}") | ||
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| totalCost | ||
| } | ||
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| // TODO can we access statistics from previous query stages? | ||
| val estimatedRowCount = 1000 | ||
| val cost = (computePlanCost(plan) * estimatedRowCount).toLong | ||
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| logWarning(s"Computed cost of $cost for $plan") | ||
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| SimpleCost(cost) | ||
| } | ||
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| } |
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67 changes: 67 additions & 0 deletions
67
spark/src/test/scala/org/apache/comet/CostBasedOptimizerSuite.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. | ||
| */ | ||
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| package org.apache.comet | ||
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| import org.apache.spark.sql.CometTestBase | ||
| import org.apache.spark.sql.execution.adaptive.AdaptiveSparkPlanHelper | ||
| import org.apache.spark.sql.internal.SQLConf | ||
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| class CostBasedOptimizerSuite extends CometTestBase with AdaptiveSparkPlanHelper { | ||
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| private val dataGen = DataGenerator.DEFAULT | ||
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| test("tbd") { | ||
| withSQLConf(SQLConf.AUTO_BROADCASTJOIN_THRESHOLD.key -> "-1", | ||
| SQLConf.COALESCE_PARTITIONS_ENABLED.key -> "false", | ||
| CometConf.COMET_ENABLED.key -> "true", | ||
| CometConf.COMET_EXEC_ENABLED.key -> "true", | ||
| CometConf.COMET_EXEC_SHUFFLE_ENABLED.key -> "true", | ||
| CometConf.COMET_CBO_ENABLED.key -> "true", | ||
| CometConf.COMET_EXPLAIN_FALLBACK_ENABLED.key -> "true") { | ||
| val table = "t1" | ||
| withTable(table, "t2") { | ||
| sql(s"create table t1(col string, a int, b float) using parquet") | ||
| sql(s"create table t2(col string, a int, b float) using parquet") | ||
| val tableSchema = spark.table(table).schema | ||
| val rows = dataGen.generateRows( | ||
| 1000, | ||
| tableSchema, | ||
| Some(() => dataGen.generateString("tbd:", 6))) | ||
| val data = spark.createDataFrame(spark.sparkContext.parallelize(rows), tableSchema) | ||
| data.write | ||
| .mode("append") | ||
| .insertInto(table) | ||
| data.write | ||
| .mode("append") | ||
| .insertInto("t2") | ||
| val x = checkSparkAnswer/*AndOperator*/("select t1.col as x " + | ||
| "from t1 join t2 on cast(t1.col as timestamp) = cast(t2.col as timestamp) " + | ||
| "order by x") | ||
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| // TODO assert that we fell back for whole plan | ||
| println(x._1) | ||
| println(x._2) | ||
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| assert(!x._2.toString().contains("CometSortExec")) | ||
| } | ||
| } | ||
| } | ||
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| } |