sunchao commented on code in PR #57576: URL: https://github.com/apache/spark/pull/57576#discussion_r3675946993
########## sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/CombineApproximatePercentiles.scala: ########## @@ -0,0 +1,139 @@ +/* + * 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.catalyst.optimizer + +import scala.collection.mutable + +import org.apache.spark.sql.catalyst.expressions.{CreateArray, Expression, ExprId, GetArrayItem, Literal, NamedExpression} +import org.apache.spark.sql.catalyst.expressions.aggregate.{AggregateExpression, AggregateMode, ApproximatePercentile} +import org.apache.spark.sql.catalyst.plans.logical.{Aggregate, LogicalPlan} +import org.apache.spark.sql.catalyst.rules.Rule +import org.apache.spark.sql.catalyst.trees.TreePattern.AGGREGATE +import org.apache.spark.sql.types.DoubleType + +/** + * Combines scalar approximate percentiles that can share the same percentile digest. + * + * An approximate percentile digest depends on its input, accuracy, filter, distinctness, and + * aggregate mode, but not on the percentile requested from the completed digest. Consequently, + * compatible scalar percentiles can be calculated by one array-valued aggregate and projected + * back to their original scalar outputs. + * + * Inputs and filters must retain their original expression structure so that floating-point + * evaluation and ANSI overflow behavior are preserved. Streaming aggregates are left unchanged + * to preserve the value schemas of existing checkpoints. + */ +object CombineApproximatePercentiles extends Rule[LogicalPlan] { + + private case class CompatibilityKey( + child: Expression, + accuracy: Long, + mode: AggregateMode, + isDistinct: Boolean, + filter: Option[Expression]) + + private case class PhysicalCompatibilityKey( + child: Expression, + accuracy: Expression, + mode: AggregateMode, + isDistinct: Boolean, + filter: Option[Expression]) + + private def physicalCompatibilityKey( + key: CompatibilityKey, + accuracy: Expression): PhysicalCompatibilityKey = PhysicalCompatibilityKey( + key.child.canonicalized, + accuracy.canonicalized, + key.mode, + key.isDistinct, + key.filter.map(_.canonicalized)) + + override def apply(plan: LogicalPlan): LogicalPlan = plan.transformUpWithPruning( + _.containsPattern(AGGREGATE), ruleId) { + case aggregate: Aggregate if aggregate.resolved && !aggregate.isStreaming => + combine(aggregate) + } + + private def combine(aggregate: Aggregate): Aggregate = { + val compatible = mutable.LinkedHashMap.empty[ + CompatibilityKey, mutable.ArrayBuffer[AggregateExpression]] + val physicalCompatibilityKeys = mutable.HashMap.empty[ + PhysicalCompatibilityKey, mutable.HashSet[CompatibilityKey]] + val arrayPercentiles = mutable.ArrayBuffer.empty[AggregateExpression] + + aggregate.aggregateExpressions.foreach(_.foreach { + case expression @ AggregateExpression( + percentile: ApproximatePercentile, mode, isDistinct, filter, _) + if percentile.child.deterministic && + filter.forall(_.deterministic) => + val key = CompatibilityKey( + percentile.child, + percentile.accuracyExpression.eval().asInstanceOf[Number].longValue, + mode, + isDistinct, + filter) + physicalCompatibilityKeys.getOrElseUpdate( + physicalCompatibilityKey(key, percentile.accuracyExpression), + mutable.HashSet.empty) += key + if (percentile.percentageExpression.dataType == DoubleType) { + compatible.getOrElseUpdate(key, mutable.ArrayBuffer.empty) += expression + } else { + arrayPercentiles += expression + } + case _ => + }) + + val replacements = mutable.HashMap.empty[ExprId, (AggregateExpression, Int)] + compatible.iterator.filter { case (key, expressions) => + expressions.sizeCompare(1) > 0 && expressions.forall { expression => Review Comment: Thanks, good catch. I changed the gate to use the same canonical aggregate groups that `PhysicalAggregation` already shares, rather than merely counting logical expressions. After deduplicating repeated `resultId`s, fusion now requires more than one physical group: `p50, p50` stays unfused, while `p50, p50, p90` still fuses because it removes a real digest. Canonical groups whose percentage expressions evaluate differently are rejected as well. I added optimizer and physical-plan regressions for these cases. -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
