yyanyy commented on code in PR #58298: URL: https://github.com/apache/spark/pull/58298#discussion_r4022018264
########## sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/AnalyzedSchemaProjection.scala: ########## @@ -0,0 +1,356 @@ +/* + * 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.execution.datasources.v2 + +import org.apache.spark.{SparkException, SparkThrowable} +import org.apache.spark.sql.catalyst.SQLConfHelper +import org.apache.spark.sql.catalyst.analysis.Resolver +import org.apache.spark.sql.catalyst.expressions.{Alias, ArrayTransform, AttributeReference, AttributeSeq, CreateNamedStruct, Expression, ExtractValue, GetStructField, If, IsNull, KnownNotNull, LambdaFunction, Literal, MetadataAttributeWithLogicalName, NamedLambdaVariable, TaggingExpression, TransformKeys, TransformValues, UnresolvedNamedLambdaVariable} +import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, Project} +import org.apache.spark.sql.catalyst.util.MetadataColumnHelper +import org.apache.spark.sql.types.{ArrayType, DataType, MapType, Metadata, StructType} +import org.apache.spark.sql.util.SchemaUtils + +/** + * Restores the output a plan was analyzed with on a relation whose table has since changed - the + * schema `V2TableUtil.validateCapturedColumns` calls the captured one. + * + * The relation exposes the table's current schema, so its output stays aligned with the physical + * scan, and a projection on top recreates the columns, types and expression IDs the parent plan was + * analyzed against. + */ +private[sql] object AnalyzedSchemaProjection extends SQLConfHelper { + + /** + * Prevents [[CreateNamedStruct]] from inheriting metadata from a field value while leaving the + * value's type, nullability, evaluation, and code generation unchanged. + */ + private case class MetadataPropagationBarrier(child: Expression) extends TaggingExpression { + override protected def withNewChildInternal( + newChild: Expression): MetadataPropagationBarrier = copy(child = newChild) + } + + def rebindToAnalyzedSchema(relation: DataSourceV2Relation): LogicalPlan = { + // The relation still carries the output captured at analysis time; only its table has been + // swapped for the current one. + val capturedOutput = relation.output + val resolver = conf.resolver + val caseSensitive = conf.caseSensitiveAnalysis + val current = DataSourceV2Relation.create( + relation.table, + relation.catalog, + relation.identifier, + relation.options, + relation.timeTravelSpec) + val currentMetadataOutput = current.metadataOutput + val currentMetadata = capturedOutput.filter(_.isMetadataCol).map { captured => + val logicalName = metadataLogicalName(captured) + matchFoldedName(currentMetadataOutput, logicalName, caseSensitive)(metadataLogicalName) + .map(pos => currentMetadataOutput(pos)) + .getOrElse { + // The connector still reports this metadata column, so it can only be absent here + // because a data column has taken its name and the connector suppresses rather than + // renames the conflict (`canRenameConflictingMetadataColumns`). Validation owns + // rejecting that. + unexpectedSchemaChange( + s"captured metadata column $logicalName is missing from the current relation") + } + } + + val currentOutput = current.output ++ currentMetadata + + // Refresh may visit an already rebound relation. Preserve its attributes so the projection + // above it continues to reference valid expression IDs. + // + // A further schema change on such a relation adds a second projection instead of replacing + // the first. Only the cache stores a refreshed plan, so the effect is limited to that entry: + // it stops matching the single projection a query rebuilds from its own captured output, and + // is no longer reused. Results stay correct. + if (sameOutputShape(capturedOutput, currentOutput)) { + return relation + } + + val capturedIndex = new AttributeIndex(capturedOutput, resolver, caseSensitive) + val reboundOutput = currentOutput.map { currentAttr => + capturedIndex.get(currentAttr).filter(canReuse(_, currentAttr)).getOrElse(currentAttr) + } + val reboundRelation = relation.copy(output = reboundOutput) + + val reboundIndex = new AttributeIndex(reboundOutput, resolver, caseSensitive) + val projectList = capturedOutput.map { capturedAttr => Review Comment: Good catch. I agree this case is real. It requires an already-analyzed query plus an external catalog change that adds a resolver-conflicting nested field—Spark DDL rejects this addition—and the affected captured column must be wholly unused. The result is a query failure rather than incorrect data. I looked at pruning unused outputs here, but doing that safely before optimizer pruning becomes plan-wide attribute-liveness analysis rather than a local filter. LogicalPlan.references excludes implicitly consumed attributes: unions map children by position, DISTINCT/INTERSECT/EXCEPT consume whole rows, and CTE or subquery references may use different expression IDs. Given how narrow this case is, I would prefer to handle that broader analysis in a follow-up rather than expand this PR further. I removed “safely” from the migration guide so it no longer makes the broad claim identified here. -- 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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