cloud-fan commented on a change in pull request #34929: URL: https://github.com/apache/spark/pull/34929#discussion_r779653096
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/PushdownPredicatesAndPruneColumnsForCTEDef.scala ########## @@ -0,0 +1,171 @@ +/* + * 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.{And, Attribute, AttributeSet, Expression, Literal, Or, SubqueryExpression} +import org.apache.spark.sql.catalyst.planning.ScanOperation +import org.apache.spark.sql.catalyst.plans.logical._ +import org.apache.spark.sql.catalyst.rules.Rule +import org.apache.spark.sql.catalyst.trees.TreePattern.CTE + +/** + * Infer predicates and column pruning for [[CTERelationDef]] from its reference points, and push + * the disjunctive predicates as well as the union of attributes down the CTE plan. + */ +object PushdownPredicatesAndPruneColumnsForCTEDef extends Rule[LogicalPlan] { + + // CTE_id - (CTE_definition, precedence, predicates_to_push_down, attributes_to_prune) + private type CteMap = mutable.HashMap[Long, (CTERelationDef, Int, Seq[Expression], AttributeSet)] + + override def apply(plan: LogicalPlan): LogicalPlan = { + if (!plan.isInstanceOf[Subquery] && plan.containsPattern(CTE)) { + val cteMap = new CteMap + gatherPredicatesAndAttributes(plan, cteMap) + pushdownPredicatesAndAttributes(plan, cteMap) + } else { + plan + } + } + + private def reverseMapExpressions( + input: Seq[Expression], + mapping: Map[Attribute, Expression]): Seq[Expression] = { + input.map(e => e.transform { + case a: Attribute => + mapping.keys.find(_.semanticEquals(a)).map(mapping).getOrElse(a) + }) + } + + /** + * Gather all the predicates and referenced attributes on different points of CTE references + * using pattern `ScanOperation` (which takes care of determinism) and combine those predicates + * and attributes that belong to the same CTE definition. + * For the same CTE definition, if any of its references does not have predicates, the combined + * predicate will be a TRUE literal, which means there will be no predicate push-down. + */ + private def gatherPredicatesAndAttributes(plan: LogicalPlan, cteMap: CteMap): Unit = { + plan match { + case WithCTE(child, cteDefs) => + cteDefs.zipWithIndex.foreach { case (cteDef, precedence) => + gatherPredicatesAndAttributes(cteDef.child, cteMap) + cteMap.put(cteDef.id, (cteDef, precedence, Seq.empty, AttributeSet.empty)) + } + gatherPredicatesAndAttributes(child, cteMap) + + case ScanOperation(projects, predicates, ref: CTERelationRef) => + val (cteDef, precedence, preds, attrs) = cteMap(ref.cteId) + val mapping = ref.output.zip(cteDef.output).map{ case (r, d) => r -> d }.toMap Review comment: ```suggestion val mapping = ref.output.zip(cteDef.output).map { case (r, d) => r -> d }.toMap ``` -- 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]
