cloud-fan commented on a change in pull request #29101: URL: https://github.com/apache/spark/pull/29101#discussion_r455695315
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/PushExtraPredicateThroughJoin.scala ########## @@ -0,0 +1,113 @@ +/* + * 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 org.apache.spark.sql.catalyst.expressions.{And, Expression, PredicateHelper} +import org.apache.spark.sql.catalyst.plans._ +import org.apache.spark.sql.catalyst.plans.logical.{Filter, Join, LogicalPlan} +import org.apache.spark.sql.catalyst.rules.Rule +import org.apache.spark.sql.catalyst.trees.TreeNodeTag + +/** + * Try converting join condition to conjunctive normal form expression so that more predicates may + * be able to be pushed down. + * To avoid expanding the join condition, the join condition will be kept in the original form even + * when predicate pushdown happens. + */ +object PushExtraPredicateThroughJoin extends Rule[LogicalPlan] with PredicateHelper { + + private val processedJoinConditionTag = TreeNodeTag[Expression]("processedJoinCondition") + + private def canPushThrough(joinType: JoinType): Boolean = joinType match { + case _: InnerLike | LeftSemi | RightOuter | LeftOuter | LeftAnti | ExistenceJoin(_) => true + case _ => false + } + + /** + * Splits join condition expressions or filter predicates (on a given join's output) into three + * categories based on the attributes required to evaluate them. Note that we explicitly exclude + * non-deterministic (i.e., stateful) condition expressions in canEvaluateInLeft or + * canEvaluateInRight to prevent pushing these predicates on either side of the join. + * + * @return (canEvaluateInLeft, canEvaluateInRight, haveToEvaluateInBoth) + */ + protected def extractConvertibleFilters( + condition: Seq[Expression], + left: LogicalPlan, + right: LogicalPlan): (Seq[Expression], Seq[Expression], Seq[Expression]) = { + val (pushDownCandidates, nonDeterministic) = condition.partition(_.deterministic) + val (leftEvaluateCondition, rest) = + pushDownCandidates.partition(_.references.subsetOf(left.outputSet)) + val (rightEvaluateCondition, commonCondition) = + rest.partition(expr => expr.references.subsetOf(right.outputSet)) + + // For the predicates in `commonCondition`, it is still possible to find sub-predicates which + // are able to be pushed down. + val leftExtraCondition = + commonCondition.flatMap(convertibleFilter(_, left.outputSet)) + + val rightExtraCondition = + commonCondition.flatMap(convertibleFilter(_, right.outputSet)) + + // To avoid expanding the join condition into conjunctive normal form and making the size + // of codegen much larger, `commonCondition` will be kept as original form in the new join + // condition. + (leftEvaluateCondition ++ leftExtraCondition, rightEvaluateCondition ++ rightExtraCondition, + commonCondition ++ nonDeterministic) + } + + def apply(plan: LogicalPlan): LogicalPlan = plan transform { + case j @ Join(left, right, joinType, Some(joinCondition), hint) + if canPushThrough(joinType) => + val filtersOfBothSide = splitConjunctivePredicates(joinCondition).filter { f => + f.deterministic && f.references.nonEmpty && + !f.references.subsetOf(left.outputSet) && !f.references.subsetOf(right.outputSet) + } + val leftExtraCondition = + filtersOfBothSide.flatMap(convertibleFilter(_, left.outputSet)) + + val rightExtraCondition = + filtersOfBothSide.flatMap(convertibleFilter(_, right.outputSet)) + + val alreadyProcessed = j.getTagValue(processedJoinConditionTag).exists { condition => Review comment: shall we do this earlier? to quit earlier ---------------------------------------------------------------- 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: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
