cloud-fan commented on code in PR #45383: URL: https://github.com/apache/spark/pull/45383#discussion_r1544061247
########## sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CollationTypeCasts.scala: ########## @@ -0,0 +1,160 @@ +/* + * 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.analysis + +import javax.annotation.Nullable + +import scala.annotation.tailrec + +import org.apache.spark.sql.catalyst.expressions.{BinaryExpression, Cast, Collate, ComplexTypeMergingExpression, CreateArray, ExpectsInputTypes, Expression, Predicate, SortOrder} +import org.apache.spark.sql.errors.QueryCompilationErrors +import org.apache.spark.sql.internal.SQLConf +import org.apache.spark.sql.types.{AbstractDataType, ArrayType, DataType, StringType} + +object CollationTypeCasts extends TypeCoercionRule { + override val transform: PartialFunction[Expression, Expression] = { + case e if !e.childrenResolved => e + // Case when we do fail if resulting collation is indeterminate + case checkCastWithoutIndeterminate @ (_: BinaryExpression + | _: Predicate + | _: SortOrder + | _: ExpectsInputTypes + | _: ComplexTypeMergingExpression + | _: CreateArray) + if shouldCast(checkCastWithoutIndeterminate.children) => + val newChildren = collateToSingleType(checkCastWithoutIndeterminate.children) + checkCastWithoutIndeterminate.withNewChildren(newChildren) + } + + def shouldCast(types: Seq[Expression]): Boolean = { + types.filter(e => hasStringType(e.dataType)) + .map(e => extractStringType(e.dataType).collationId).distinct.size > 1 + } + + /** + * Checks whether given data type contains StringType. + */ + @tailrec + def hasStringType(dt: DataType): Boolean = dt match { + case _: StringType => true + case ArrayType(et, _) => hasStringType(et) + case _ => false + } + + /** + * Extracts StringTypes from filtered hasStringType + */ + @tailrec + private def extractStringType(dt: DataType): StringType = dt match { + case st: StringType => st + case ArrayType(et, _) => extractStringType(et) + } + + /** + * Casts given expression to collated StringType with id equal to collationId only + * if expression has StringType in the first place. + * @param expr + * @param collationId + * @return + */ + def castStringType(expr: Expression, collationId: Int): Option[Expression] = + castStringType(expr.dataType, collationId).map { dt => + if (dt == expr.dataType) expr else Cast(expr, dt) + } + + private def castStringType(inType: AbstractDataType, collationId: Int): Option[DataType] = { + @Nullable val ret: DataType = inType match { + case st: StringType if st.collationId == collationId => st + case _: StringType => StringType(collationId) + case ArrayType(arrType, nullable) => + castStringType(arrType, collationId).map(ArrayType(_, nullable)).orNull + case _ => null + } + Option(ret) + } + + /** + * Collates input expressions to a single collation. + */ + def collateToSingleType(exprs: Seq[Expression]): Seq[Expression] = { + val collationId = getOutputCollation(exprs) + + exprs.map(e => castStringType(e, collationId).getOrElse(e)) + } + + /** + * Based on the data types of the input expressions this method determines + * a collation type which the output will have. This function accepts Seq of + * any expressions, but will only be affected by collated StringTypes or + * complex DataTypes with collated StringTypes (e.g. ArrayType) + */ + def getOutputCollation(exprs: Seq[Expression]): Int = { + val explicitTypes = exprs.filter(hasExplicitCollation) + .map(e => extractStringType(e.dataType).collationId).distinct + + explicitTypes.size match { + // We have 1 explicit collation + case 1 => explicitTypes.head + // Multiple explicit collations occurred + case size if size > 1 => + throw QueryCompilationErrors + .explicitCollationMismatchError( + explicitTypes.map(t => StringType(t).typeName) + ) + // Only implicit or default collations present + case 0 => + val dataTypes = exprs.filter(e => hasStringType(e.dataType)) + .map(e => extractStringType(e.dataType)) + + if (hasMultipleImplicits(dataTypes)) { + throw QueryCompilationErrors.implicitCollationMismatchError() + } + else { + dataTypes.find(dt => !(dt == SQLConf.get.defaultStringType)) + .getOrElse(SQLConf.get.defaultStringType) + .collationId + } + } + } + + /** + * This check is always preformed when we have no explicit collation. It returns true + * if there are more than one implicit collations. Collations are distinguished by their + * collationId. + * @param dataTypes + * @return + */ + private def hasMultipleImplicits(dataTypes: Seq[StringType]): Boolean = + dataTypes.filter(dt => !(dt == SQLConf.get.defaultStringType)) + .map(_.collationId).distinct.size > 1 + + /** + * Checks if a given expression has explicitly set collation. For complex DataTypes + * we need to check nested children. + * @param expression + * @return + */ + private def hasExplicitCollation(expression: Expression): Boolean = { + expression match { + case _: Collate => true + case e if e.dataType.isInstanceOf[ArrayType] + => expression.children.exists(hasExplicitCollation) Review Comment: This looks a bit hacky. What is the exact definition of explicit collation? -- 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. 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