stefankandic commented on code in PR #48962: URL: https://github.com/apache/spark/pull/48962#discussion_r1862243308
########## sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/ResolveDefaultStringTypes.scala: ########## @@ -0,0 +1,216 @@ +/* + * 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 org.apache.spark.sql.catalyst.expressions.{Cast, Expression, Literal} +import org.apache.spark.sql.catalyst.plans.logical.{AddColumns, AlterColumn, AlterViewAs, ColumnDefinition, CreateView, LogicalPlan, QualifiedColType, ReplaceColumns, V1CreateTablePlan, V2CreateTablePlan} +import org.apache.spark.sql.catalyst.rules.{Rule, RuleExecutor} +import org.apache.spark.sql.internal.SQLConf +import org.apache.spark.sql.types.{DataType, StringType} + +/** + * Resolves default string types in DDL commands. For DML commands, the default string type is + * determined by the session's default string type. For DDL, the default string type is the + * default type of the object (table -> schema -> catalog). However, this is not implemented yet. + * So, we will just use UTF8_BINARY for now. + * + * `replaceWithTempType` is a flag that determines whether to replace the default string type with a + * [[TemporaryStringType]] object in cases where the old type and new are equal and thus would + * not change the plan after transformation. + */ +class ResolveDefaultStringTypes(replaceWithTempType: Boolean) extends Rule[LogicalPlan] { + def apply(plan: LogicalPlan): LogicalPlan = { + + val newPlan = if (isDDLCommand(plan)) { + transformDDL(plan) + } else { + transformPlan(plan, stringTypeForDMLCommand) + } + + if (!replaceWithTempType || newPlan.fastEquals(plan)) { + newPlan + } else { + // Due to how tree transformations work and StringType object being equal to + // StringType("UTF8_BINARY"), we need to run `ResolveDefaultStringType` twice + // to ensure the correct results for occurrences of default string type. + val finalPlan = ResolveDefaultStringTypesWithoutTempType.apply(newPlan) + RuleExecutor.forceAdditionalIteration(finalPlan) + finalPlan + } + } + + /** + * Returns whether any of the given `plan` needs to have its + * default string type resolved. + */ + def needsResolution(plan: LogicalPlan): Boolean = { + if (isDDLCommand(plan)) { + return true + } else if (isDefaultSessionCollationUsed) { + return false + } + + plan.exists(node => needsResolution(node.expressions)) + } + + /** + * Returns whether any of the given `expressions` needs to have its + * default string type resolved. + */ + def needsResolution(expressions: Seq[Expression]): Boolean = { + expressions.exists(needsResolution) + } + + /** + * Returns whether the given `expression` needs to have its + * default string type resolved. + */ + def needsResolution(expression: Expression): Boolean = { + expression.exists(e => transformExpression.isDefinedAt(e, StringType)) + } + + private def isDefaultSessionCollationUsed: Boolean = SQLConf.get.defaultStringType == StringType + + /** + * Returns the default string type that should be used in a given DDL command (for now always + * UTF8_BINARY). + */ + private def stringTypeForDDLCommand(table: LogicalPlan): StringType = + StringType("UTF8_BINARY") + + /** Returns the default string type that should be used in DML commands. */ + private def stringTypeForDMLCommand: StringType = + if (isDefaultSessionCollationUsed) { + StringType("UTF8_BINARY") + } else { + SQLConf.get.defaultStringType + } + + private def isDDLCommand(plan: LogicalPlan): Boolean = plan exists { + case _: AddColumns | _: ReplaceColumns | _: AlterColumn => true + case _ => isCreateOrAlterPlan(plan) + } + + private def isCreateOrAlterPlan(plan: LogicalPlan): Boolean = plan match { + case _: V1CreateTablePlan | _: V2CreateTablePlan | _: CreateView | _: AlterViewAs => true + case _ => false + } + + private def transformDDL(plan: LogicalPlan): LogicalPlan = { + val newType = stringTypeForDDLCommand(plan) + + plan resolveOperators { + case p if isCreateOrAlterPlan(p) => + transformPlan(p, newType) + + case addCols: AddColumns => + addCols.copy(columnsToAdd = replaceColumnTypes(addCols.columnsToAdd, newType)) + + case replaceCols: ReplaceColumns => + replaceCols.copy(columnsToAdd = replaceColumnTypes(replaceCols.columnsToAdd, newType)) + + case alter: AlterColumn + if alter.dataType.isDefined && hasDefaultStringType(alter.dataType.get) => + alter.copy(dataType = Some(replaceDefaultStringType(alter.dataType.get, newType))) + } + } + + /** + * Transforms the given plan, by transforming all expressions in its operators to use the given + * new type instead of the default string type. + */ + private def transformPlan(plan: LogicalPlan, newType: StringType): LogicalPlan = { + plan resolveOperators { operator => + operator resolveExpressionsUp { expression => + transformExpression.applyOrElse((expression, newType), fallbackToExpression) + } + } + } + + private def fallbackToExpression(tuple: (Expression, StringType)): Expression = tuple._1 + + /** + * Transforms the given expression, by changing all default string types to the given new type. + */ + private def transformExpression: PartialFunction[(Expression, StringType), Expression] = { + case (columnDef: ColumnDefinition, newType) if hasDefaultStringType(columnDef.dataType) => + columnDef.copy(dataType = replaceDefaultStringType(columnDef.dataType, newType)) + + case (cast: Cast, newType) if hasDefaultStringType(cast.dataType) => + cast.copy(dataType = replaceDefaultStringType(cast.dataType, newType)) + + case (Literal(value, dt), newType) if hasDefaultStringType(dt) => + Literal(value, replaceDefaultStringType(dt, newType)) + } + + private def hasDefaultStringType(dataType: DataType): Boolean = + dataType.existsRecursively(isDefaultStringType) + + private def isDefaultStringType(dataType: DataType): Boolean = { + dataType match { + case _: TemporaryStringType => + !replaceWithTempType + case st: StringType => + // should only return true for StringType object and not StringType("UTF8_BINARY") + st.eq(StringType) + case _ => false + } + } + + private def replaceDefaultStringType(dataType: DataType, newType: StringType): DataType = { + dataType.transformRecursively { + case currentType: StringType if isDefaultStringType(currentType) => + if (replaceWithTempType && currentType == newType) { + getTemporaryStringType(currentType) + } else { + newType + } + } + } + + private def getTemporaryStringType(forType: StringType): StringType = { + if (forType == StringType) { + TemporaryStringType(StringType("UTF8_LCASE").collationId) + } else { + TemporaryStringType(StringType.collationId) + } + } + + private def replaceColumnTypes( + colTypes: Seq[QualifiedColType], + newType: StringType): Seq[QualifiedColType] = { + colTypes.map { + case colWithDefault if hasDefaultStringType(colWithDefault.dataType) => + val replaced = replaceDefaultStringType(colWithDefault.dataType, newType) + colWithDefault.copy(dataType = replaced) + + case col => col + } + } +} + +case object ResolveDefaultStringTypes + extends ResolveDefaultStringTypes(replaceWithTempType = true) {} + +case object ResolveDefaultStringTypesWithoutTempType Review Comment: Thanks for pointing out the error in resolve, now we can make it much simpler like you mentioned above! -- This is an automated message from the Apache Git Service. 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