hvanhovell commented on a change in pull request #23388: [SPARK-26448][SQL] retain the difference between 0.0 and -0.0 URL: https://github.com/apache/spark/pull/23388#discussion_r244421992
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/NormalizeFloatingNumbers.scala ########## @@ -0,0 +1,179 @@ +/* + * 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.{Alias, And, ArrayTransform, CreateArray, CreateMap, CreateNamedStruct, CreateNamedStructUnsafe, CreateStruct, EqualTo, ExpectsInputTypes, Expression, GetStructField, LambdaFunction, NamedLambdaVariable, UnaryExpression} +import org.apache.spark.sql.catalyst.expressions.codegen.{CodegenContext, ExprCode} +import org.apache.spark.sql.catalyst.planning.ExtractEquiJoinKeys +import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, Subquery, Window} +import org.apache.spark.sql.catalyst.rules.Rule +import org.apache.spark.sql.types._ + +/** + * We need to take care of special floating numbers (NaN and -0.0) in several places: + * 1. When compare values, different NaNs should be treated as same, `-0.0` and `0.0` should be + * treated as same. + * 2. In GROUP BY, different NaNs should belong to the same group, -0.0 and 0.0 should belong + * to the same group. + * 3. In join keys, different NaNs should be treated as same, `-0.0` and `0.0` should be + * treated as same. + * 4. In window partition keys, different NaNs should be treated as same, `-0.0` and `0.0` + * should be treated as same. + * + * Case 1 is fine, as we handle NaN and -0.0 well during comparison. For complex types, we + * recursively compare the fields/elements, so it's also fine. + * + * Case 2, 3 and 4 are problematic, as they compare `UnsafeRow` binary directly, and different + * NaNs have different binary representation, and the same thing happens for -0.0 and 0.0. + * + * This rule normalizes NaN and -0.0 in Window partition keys, Join keys and Aggregate grouping + * expressions. + */ +object NormalizeFloatingNumbers extends Rule[LogicalPlan] { + + def apply(plan: LogicalPlan): LogicalPlan = plan match { + // A subquery will be rewritten into join later, and will go through this rule + // eventually. Here we skip subquery, as we only need to run this rule once. + case _: Subquery => plan + + case _ => plan transform { + case w: Window if w.partitionSpec.exists(p => needNormalize(p.dataType)) => + w.copy(partitionSpec = w.partitionSpec.map(normalize)) + + case j @ ExtractEquiJoinKeys(_, leftKeys, rightKeys, condition, _, _) + if leftKeys.exists(k => needNormalize(k.dataType)) => + val newLeftJoinKeys = leftKeys.map(normalize) + val newRightJoinKeys = rightKeys.map(normalize) + val newConditions = newLeftJoinKeys.zip(newRightJoinKeys).map { + case (l, r) => EqualTo(l, r) + } ++ condition + j.copy(condition = Some(newConditions.reduce(And))) + + // TODO: ideally Aggregate should also be handled here, but its grouping expressions are Review comment: At some point we should consider change Aggregate into something where it is easier and safer to manipulate either the grouping expressions or the aggregate expressions. Another example of this is https://issues.apache.org/jira/browse/SPARK-25914. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
