mihailom-db commented on code in PR #45383: URL: https://github.com/apache/spark/pull/45383#discussion_r1547843264
########## sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CollationTypeCasts.scala: ########## @@ -0,0 +1,152 @@ +/* + * 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.analysis.TypeCoercion.hasStringType +import org.apache.spark.sql.catalyst.expressions.{ArrayJoin, BinaryExpression, Cast, Collate, ComplexTypeMergingExpression, ConcatWs, CreateArray, Expression, In, InSubquery, Substring} +import org.apache.spark.sql.errors.QueryCompilationErrors +import org.apache.spark.sql.internal.SQLConf +import org.apache.spark.sql.types.{AbstractDataType, ArrayType, DataType, StringType} + +abstract class CollationTypeCasts extends TypeCoercionRule { + /** + * 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, st: StringType): Option[Expression] = + castStringType(expr.dataType, st).map { dt => Cast(expr, dt)} + + private def castStringType(inType: AbstractDataType, castType: StringType): Option[DataType] = { + @Nullable val ret: DataType = inType match { + case st: StringType if st.collationId != castType.collationId => castType + case ArrayType(arrType, nullable) => + castStringType(arrType, castType).map(ArrayType(_, nullable)).orNull + case _ => null + } + Option(ret) + } + + /** + * Collates input expressions to a single collation. + */ + def collateToSingleType(exprs: Seq[Expression]): Seq[Expression] = { + val st = getOutputCollation(exprs) + + exprs.map(e => castStringType(e, st).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(expr: Seq[Expression]): StringType = { + val explicitTypes = expr.filter(_.isInstanceOf[Collate]) + .map(_.dataType.asInstanceOf[StringType].collationId) + .distinct + + explicitTypes.size match { + // We have 1 explicit collation + case 1 => StringType(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 implicitTypes = expr.map(_.dataType) + .filter(hasStringType) + .map(extractStringType) + .filter(dt => dt.collationId != SQLConf.get.defaultStringType.collationId) Review Comment: There is one problem with this. We said collations are only different if their collationId's are different. If we do this, we would need to change the line in else clause to something that does not look so nice. I have changed this structure in https://github.com/apache/spark/pull/45819, which is a followup for this PR. -- 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. To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
