gengliangwang commented on code in PR #58298: URL: https://github.com/apache/spark/pull/58298#discussion_r4019082641
########## sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/AnalyzedSchemaProjection.scala: ########## @@ -0,0 +1,310 @@ +/* + * 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 +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, CreateNamedStruct, Expression, 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} + +/** + * Rebinds a relation that reads a current table schema to output attributes captured from an + * earlier compatible schema. The current schema is exposed by the relation so its output remains + * aligned with the physical scan, while a projection recreates the captured output for the + * already-analyzed parent plan. + */ +private[sql] object CapturedSchemaProjection 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 rebindToCapturedSchema(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 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) + matchName(currentMetadataOutput, logicalName, resolver)(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) + 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) + val projectList = capturedOutput.map { capturedAttr => + val currentAttr = reboundIndex.get(capturedAttr).getOrElse { + unexpectedSchemaChange( + s"captured column ${capturedAttr.name} is missing from current table ${relation.name}") + } + if (currentAttr.exprId == capturedAttr.exprId && + sameAttributeShape(currentAttr, capturedAttr)) { + currentAttr + } else { + if (currentAttr.nullable != capturedAttr.nullable) { + unexpectedSchemaChange( + s"nullability changed for captured column ${capturedAttr.name} in ${relation.name}") + } + val projected = projectToType( + currentAttr, currentAttr.dataType, capturedAttr.dataType, resolver) + if (projected.dataType != capturedAttr.dataType || + projected.nullable != capturedAttr.nullable) { + unexpectedSchemaChange( + s"failed to recreate captured column ${capturedAttr.name} in ${relation.name}") + } + Alias(projected, capturedAttr.name)( + exprId = capturedAttr.exprId, + qualifier = capturedAttr.qualifier, + explicitMetadata = Some(capturedAttr.metadata)) + } + } + + Project(projectList, reboundRelation) + } + + private[v2] def projectToType( + input: Expression, + from: DataType, + to: DataType, + resolver: Resolver): Expression = { + if (from == to) { + return input + } + + val projected = (from, to) match { + case (fromStruct: StructType, toStruct: StructType) => Review Comment: [P1] Avoid evaluating unselected sibling fields This is also a correctness issue, not only a wider-read or pushdown regression. The nullable `If` prevents `SimplifyExtractValueOps` from discarding sibling fields from the rebuilt struct. If a stale query selects only `payload.x`, while sibling `payload.m` is a map whose struct key gained a field, evaluating the reconstructed `payload` still runs `TransformKeys` for `m`; two keys distinguished only by the added field then throw `DUPLICATED_MAP_KEY`. A fresh query selecting `payload.x` never evaluates `m`. Please fix the projection shape in this PR, or make reconstruction usage-aware, so unselected nested fields are not evaluated. -- 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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