sunchao commented on a change in pull request #29565: URL: https://github.com/apache/spark/pull/29565#discussion_r479458937
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/UnwrapCast.scala ########## @@ -0,0 +1,155 @@ +/* + * 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._ +import org.apache.spark.sql.catalyst.expressions.Literal.FalseLiteral +import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan +import org.apache.spark.sql.catalyst.rules.Rule +import org.apache.spark.sql.types._ + +/** + * Unwrap casts in binary comparison operations with the following pattern: + * `BinaryComparison(Cast(fromExp, _), Literal(value, toType))` + * This rule optimize expressions with this pattern by either replacing the cast with simpler + * constructs, or moving the cast from the expression side to the literal side, so they can be + * optimized away and pushed down to data sources. + * + * Currently this only handles the case where `fromType` (of `fromExp`) and `toType` are of + * integral types (i.e., byte, short, int and long). It checks to see if the literal `value` is + * within range (min, max) of the `fromType`. If this is true then it means we can safely cast the + * `value` to the `fromType` and thus able to move the cast to the literal side. Otherwise, it + * replaces the cast with different simpler constructs, such as + * `EqualTo(fromExp, Literal(max, fromType)` when input is + * `GreaterThanOrEqualTo(Cast(fromExp, fromType), Literal(max, toType))` + */ +object UnwrapCast extends Rule[LogicalPlan] { + override def apply(plan: LogicalPlan): LogicalPlan = plan transform { + case l: LogicalPlan => l transformExpressionsUp { + case e @ BinaryComparison(_, _) => unwrapCast(e) + } + } + + private def unwrapCast(exp: Expression): Expression = exp match { + case BinaryComparison(Literal(_, _), Cast(_, _, _)) => + def swap(e: Expression): Expression = e match { + case GreaterThan(left, right) => LessThan(right, left) + case GreaterThanOrEqual(left, right) => LessThanOrEqual(right, left) + case EqualTo(left, right) => EqualTo(right, left) + case EqualNullSafe(left, right) => EqualNullSafe(right, left) + case LessThanOrEqual(left, right) => GreaterThanOrEqual(right, left) + case LessThan(left, right) => GreaterThan(right, left) + case other => other + } + swap(unwrapCast(swap(exp))) + + case BinaryComparison(Cast(fromExp, _, _), Literal(value, toType)) => Review comment: 👍 yup will do this ---------------------------------------------------------------- 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]
