wangyum commented on a change in pull request #30865: URL: https://github.com/apache/spark/pull/30865#discussion_r548340610
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/SimplifyConditionalsInPredicate.scala ########## @@ -0,0 +1,78 @@ +/* + * 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, CaseWhen, Expression, If, Literal, Not, Or} +import org.apache.spark.sql.catalyst.expressions.Literal.{FalseLiteral, TrueLiteral} +import org.apache.spark.sql.catalyst.plans.logical._ +import org.apache.spark.sql.catalyst.rules.Rule +import org.apache.spark.sql.types.BooleanType + +/** + * A rule that converting conditional expressions to predicate expressions, if possible, in the + * search condition of the WHERE/HAVING/ON(JOIN) clauses, which contain an implicit Boolean operator + * "(search condition) = TRUE". After this converting, we can potentially push the filter down to + * the data source. + * + * Supported cases are: + * - IF(cond, trueVal, false) => AND(cond, trueVal) + * - IF(cond, trueVal, true) => OR(NOT(cond), trueVal) + * - IF(cond, false, falseVal) => AND(NOT(cond), elseVal) + * - IF(cond, true, falseVal) => OR(cond, elseVal) + * - CASE WHEN cond THEN trueVal ELSE false END => AND(cond, trueVal) + * - CASE WHEN cond THEN trueVal END => AND(cond, trueVal) + * - CASE WHEN cond THEN trueVal ELSE null END => AND(cond, trueVal) + * - CASE WHEN cond THEN trueVal ELSE true END => OR(NOT(cond), trueVal) + * - CASE WHEN cond THEN false ELSE elseVal END => AND(NOT(cond), elseVal) + * - CASE WHEN cond THEN false END => AND(NOT(cond), false) + * - CASE WHEN cond THEN true ELSE elseVal END => OR(cond, elseVal) + * - CASE WHEN cond THEN true END => OR(cond, false) + */ +object SimplifyConditionalsInPredicate extends Rule[LogicalPlan] { + + def apply(plan: LogicalPlan): LogicalPlan = plan transform { + case f @ Filter(cond, _) => f.copy(condition = simplifyConditional(cond)) + case j @ Join(_, _, _, Some(cond), _) => j.copy(condition = Some(simplifyConditional(cond))) + case d @ DeleteFromTable(_, Some(cond)) => d.copy(condition = Some(simplifyConditional(cond))) + case u @ UpdateTable(_, _, Some(cond)) => u.copy(condition = Some(simplifyConditional(cond))) + } + + private def simplifyConditional(e: Expression): Expression = e match { + case And(left, right) => And(simplifyConditional(left), simplifyConditional(right)) + case Or(left, right) => Or(simplifyConditional(left), simplifyConditional(right)) + case If(cond, trueValue, FalseLiteral) => And(cond, trueValue) + case If(cond, trueValue, TrueLiteral) => Or(Not(cond), trueValue) + case If(cond, FalseLiteral, falseValue) => And(Not(cond), falseValue) + case If(cond, TrueLiteral, falseValue) => Or(cond, falseValue) + case CaseWhen(Seq((cond, trueValue)), + Some(FalseLiteral) | Some(Literal(null, BooleanType)) | None) => + And(cond, trueValue) + case CaseWhen(Seq((cond, trueValue)), Some(TrueLiteral)) => + Or(Not(cond), trueValue) + case CaseWhen(Seq((cond, FalseLiteral)), elseValue) => + And(Not(cond), elseValue.getOrElse(FalseLiteral)) Review comment: We can further optimize it to: ```scala case CaseWhen(Seq((cond, FalseLiteral)), elseValue) => elseValue.map(And(Not(cond), _)).getOrElse(FalseLiteral) ``` ---------------------------------------------------------------- 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]
