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[SPARK-55952][SPARK-55953][SQL] Add ResolveChangelogTable analyzer rule for batch CDC post-processing #55508
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312 changes: 312 additions & 0 deletions
312
...atalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/ResolveChangelogTable.scala
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| /* | ||
| * 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. | ||
| */ | ||
|
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| package org.apache.spark.sql.catalyst.analysis | ||
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| import org.apache.spark.sql.catalyst.expressions._ | ||
| import org.apache.spark.sql.catalyst.expressions.aggregate.{Count, Max, Min} | ||
| import org.apache.spark.sql.catalyst.plans.logical._ | ||
| import org.apache.spark.sql.catalyst.rules.Rule | ||
| import org.apache.spark.sql.catalyst.streaming.StreamingRelationV2 | ||
| import org.apache.spark.sql.connector.catalog.{Changelog, ChangelogInfo} | ||
| import org.apache.spark.sql.errors.QueryCompilationErrors | ||
| import org.apache.spark.sql.execution.datasources.v2.{ChangelogTable, DataSourceV2Relation} | ||
| import org.apache.spark.sql.types.{IntegerType, StringType} | ||
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| /** | ||
| * Post-processes a resolved [[ChangelogTable]] read to apply CDC option semantics | ||
| * (carry-over removal, update detection) and to enforce supported option combinations. | ||
| * | ||
| * Fires after [[ResolveRelations]] has wrapped the connector's [[Changelog]] in a | ||
| * [[ChangelogTable]]. Both batch ([[DataSourceV2Relation]]) and streaming | ||
| * ([[StreamingRelationV2]]) reads are handled: | ||
| * - Batch: the requested post-processing passes are injected as logical operators on top | ||
| * of the relation. Carry-over removal and update detection are fused into a single | ||
| * pass over a (rowId, _commit_version)-partitioned Window: the Filter drops CoW | ||
| * carry-over pairs (same rowVersion on both sides) and the subsequent Project relabels | ||
| * real delete+insert pairs as update_preimage / update_postimage. | ||
| * - Streaming: post-processing is not yet supported. If the requested options would | ||
| * require any post-processing, the rule throws an explicit [[AnalysisException]] to | ||
| * prevent silent wrong results. Streams that don't require post-processing pass | ||
| * through unchanged. | ||
| * | ||
| * Net change computation (`deduplicationMode = netChanges`) is not yet implemented and | ||
| * is rejected up-front for both batch and streaming. | ||
| */ | ||
| object ResolveChangelogTable extends Rule[LogicalPlan] { | ||
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|
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| /** | ||
| * Reserved (`__spark_cdc_*`) column names used internally by post-processing; | ||
| * connectors must not emit columns with these names. | ||
| */ | ||
| object HelperColumn { | ||
| final val DelCnt = "__spark_cdc_del_cnt" | ||
| final val InsCnt = "__spark_cdc_ins_cnt" | ||
| final val MinRv = "__spark_cdc_min_rv" | ||
| final val MaxRv = "__spark_cdc_max_rv" | ||
| final val RvCnt = "__spark_cdc_rv_cnt" | ||
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| val all: Set[String] = Set(DelCnt, InsCnt, MinRv, MaxRv, RvCnt) | ||
| } | ||
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| override def apply(plan: LogicalPlan): LogicalPlan = plan.resolveOperatorsUp { | ||
| case rel @ DataSourceV2Relation(table: ChangelogTable, _, _, _, _, _) if !table.resolved => | ||
| val changelog = table.changelog | ||
| val req = evaluateRequirements(changelog, table.changelogInfo) | ||
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| val resolvedRel = rel.copy(table = table.copy(resolved = true)) | ||
| var updatedRel: LogicalPlan = resolvedRel | ||
| if (req.requiresCarryOverRemoval || req.requiresUpdateDetection) { | ||
| updatedRel = addRowLevelPostProcessing( | ||
| resolvedRel, changelog, req.requiresCarryOverRemoval, req.requiresUpdateDetection) | ||
| } | ||
| if (req.requiresNetChanges) { | ||
| updatedRel = injectNetChangeComputation(updatedRel, changelog) | ||
| } | ||
| updatedRel | ||
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| case rel @ StreamingRelationV2(_, _, table: ChangelogTable, _, _, _, _, _, _) | ||
| if !table.resolved => | ||
| // Streaming CDC reads do not yet apply post-processing. Run the same option / | ||
| // capability validation as the batch path so silent wrong results are impossible: | ||
| // either no post-processing would be required (fall through, return raw stream), | ||
| // or we throw an explicit AnalysisException. | ||
| val changelog = table.changelog | ||
| val req = evaluateRequirements(changelog, table.changelogInfo) | ||
| if (req.needsAny) { | ||
| throw QueryCompilationErrors.cdcStreamingPostProcessingNotSupported(changelog.name()) | ||
| } | ||
| rel.copy(table = table.copy(resolved = true)) | ||
| } | ||
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| // --------------------------------------------------------------------------- | ||
| // Option validation & Requirement Computation | ||
| // --------------------------------------------------------------------------- | ||
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| /** | ||
| * Captures which post-processing passes a CDC query requires, derived from the | ||
| * user-provided [[ChangelogInfo]] options and the connector-declared [[Changelog]] | ||
| * capability flags. | ||
| */ | ||
| private case class PostProcessingRequirements( | ||
| requiresCarryOverRemoval: Boolean, | ||
| requiresUpdateDetection: Boolean, | ||
| requiresNetChanges: Boolean) { | ||
| def needsAny: Boolean = | ||
| requiresCarryOverRemoval || requiresUpdateDetection || requiresNetChanges | ||
| } | ||
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| /** | ||
| * Validates CDC option/capability combinations and computes which post-processing | ||
| * passes are required. Throws an [[org.apache.spark.sql.AnalysisException]] for | ||
| * unsupported or contradictory combinations (currently: `netChanges` deduplication, | ||
| * and `computeUpdates` with surfaced carry-overs but no carry-over removal). | ||
| */ | ||
| private def evaluateRequirements( | ||
| changelog: Changelog, | ||
| options: ChangelogInfo): PostProcessingRequirements = { | ||
| // Net change computation is not yet implemented. | ||
| if (options.deduplicationMode() == ChangelogInfo.DeduplicationMode.NET_CHANGES) { | ||
| throw QueryCompilationErrors.cdcNetChangesNotYetSupported(changelog.name()) | ||
| } | ||
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| val requiresCarryOverRemoval = | ||
| options.deduplicationMode() != ChangelogInfo.DeduplicationMode.NONE && | ||
| changelog.containsCarryoverRows() | ||
| val requiresUpdateDetection = | ||
| options.computeUpdates() && changelog.representsUpdateAsDeleteAndInsert() | ||
| val requiresNetChanges = | ||
| options.deduplicationMode() == ChangelogInfo.DeduplicationMode.NET_CHANGES && | ||
| changelog.containsIntermediateChanges() | ||
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| // If carry-overs are surfaced and update detection is enabled without carry-over | ||
| // removal, carry-overs would be falsely classified as updates, leading to wrong | ||
| // results. Hence we throw. | ||
| if (requiresUpdateDetection && | ||
| changelog.containsCarryoverRows() && | ||
| options.deduplicationMode() == ChangelogInfo.DeduplicationMode.NONE) { | ||
| throw QueryCompilationErrors.cdcUpdateDetectionRequiresCarryOverRemoval( | ||
| changelog.name()) | ||
| } | ||
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| PostProcessingRequirements( | ||
| requiresCarryOverRemoval, requiresUpdateDetection, requiresNetChanges) | ||
| } | ||
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| // --------------------------------------------------------------------------- | ||
| // Row Level Post Processing (Update Detection & Carry-over Removal) | ||
| // --------------------------------------------------------------------------- | ||
|
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| /** | ||
| * Adds row-level post-processing (carry-over removal and/or update detection) on top of | ||
| * the given plan. `counts` = per-partition delete and insert change_type row counts over | ||
| * `(rowId, _commit_version)`. `rv bounds` = per-partition min/max of `rowVersion`. | ||
| * Equal bounds signal a copy-on-write carry-over. | ||
| * - both active -> Window(counts + rv bounds) -> Filter -> Project(relabel) -> Drop helpers | ||
| * - carry-over only -> Window(counts + rv bounds) -> Filter -> Drop helpers | ||
| * - update only -> Window(counts only) -> Project(relabel) -> Drop helpers | ||
| * - neither -> not invoked (caller guards this case) | ||
| */ | ||
| private def addRowLevelPostProcessing( | ||
| plan: LogicalPlan, | ||
| cl: Changelog, | ||
| requiresCarryOverRemoval: Boolean, | ||
| requiresUpdateDetection: Boolean): LogicalPlan = { | ||
| // Row-version bounds in the Window are needed iff we filter carry-over pairs. | ||
| var modifiedPlan = addPostProcessingWindow(plan, cl, | ||
| includeRowVersionBounds = requiresCarryOverRemoval) | ||
| if (requiresCarryOverRemoval) modifiedPlan = addCarryOverPairFilter(modifiedPlan) | ||
| if (requiresUpdateDetection) modifiedPlan = addUpdateRelabelProjection(modifiedPlan) | ||
| removeHelperColumns(modifiedPlan) | ||
| } | ||
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| /** | ||
| * Adds a Window node partitioned by (rowId, _commit_version) that computes | ||
| * `_del_cnt` and `_ins_cnt` per partition, and, when `includeRowVersionBounds` | ||
| * is true, additionally `_min_rv` / `_max_rv` / `_rv_cnt` (min, max and non-null | ||
| * count of `Changelog.rowVersion()`). | ||
| * | ||
| * `_del_cnt` / `_ins_cnt` drive update detection (1 each -> relabel as | ||
| * update_preimage / update_postimage). `_min_rv` / `_max_rv` / `_rv_cnt` drive | ||
| * carry-over detection (within a delete+insert pair, `_rv_cnt = 2` AND equal | ||
| * bounds signal a CoW carry-over). | ||
| */ | ||
| private def addPostProcessingWindow( | ||
| plan: LogicalPlan, | ||
| cl: Changelog, | ||
| includeRowVersionBounds: Boolean): LogicalPlan = { | ||
| val changeTypeAttr = getAttribute(plan, "_change_type") | ||
| val rowIdExprs = V2ExpressionUtils.resolveRefs[NamedExpression](cl.rowId().toSeq, plan) | ||
|
SanJSp marked this conversation as resolved.
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| val commitVersionAttr = getAttribute(plan, "_commit_version") | ||
| val partitionByCols = rowIdExprs ++ Seq(commitVersionAttr) | ||
| val windowSpec = WindowSpecDefinition(partitionByCols, Nil, UnspecifiedFrame) | ||
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| val insertIf = If(EqualTo(changeTypeAttr, Literal(Changelog.CHANGE_TYPE_INSERT)), | ||
| Literal(1), Literal(null, IntegerType)) | ||
| val deleteIf = If(EqualTo(changeTypeAttr, Literal(Changelog.CHANGE_TYPE_DELETE)), | ||
| Literal(1), Literal(null, IntegerType)) | ||
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| val insCntAlias = Alias(WindowExpression( | ||
| Count(Seq(insertIf)).toAggregateExpression(), windowSpec), HelperColumn.InsCnt)() | ||
| val delCntAlias = Alias(WindowExpression( | ||
| Count(Seq(deleteIf)).toAggregateExpression(), windowSpec), HelperColumn.DelCnt)() | ||
| val baseAliases = Seq(delCntAlias, insCntAlias) | ||
| val rowVersionAliases = if (includeRowVersionBounds) { | ||
| val rowVersionExpr = | ||
| V2ExpressionUtils.resolveRef[NamedExpression](cl.rowVersion(), plan) | ||
| Seq( | ||
| Alias(WindowExpression( | ||
| Min(rowVersionExpr).toAggregateExpression(), windowSpec), HelperColumn.MinRv)(), | ||
| Alias(WindowExpression( | ||
| Max(rowVersionExpr).toAggregateExpression(), windowSpec), HelperColumn.MaxRv)(), | ||
| Alias(WindowExpression( | ||
| Count(Seq(rowVersionExpr)).toAggregateExpression(), windowSpec), HelperColumn.RvCnt)()) | ||
| } else { | ||
| Seq.empty | ||
| } | ||
| Window(baseAliases ++ rowVersionAliases, partitionByCols, Nil, plan) | ||
| } | ||
|
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| /** | ||
| * Adds a Filter node that drops rows belonging to a CoW carry-over pair. | ||
| * A pair is a carry-over iff | ||
| * `_del_cnt = 1 AND _ins_cnt = 1 AND _rv_cnt = 2 AND _min_rv = _max_rv`. | ||
| * The `_rv_cnt = 2` clause guards against a NULL rowVersion silently matching | ||
| * `_min_rv = _max_rv` (Spark's min/max skip NULLs). | ||
| */ | ||
| private def addCarryOverPairFilter(input: LogicalPlan): LogicalPlan = { | ||
| val delCnt = getAttribute(input, HelperColumn.DelCnt) | ||
| val insCnt = getAttribute(input, HelperColumn.InsCnt) | ||
| val minRv = getAttribute(input, HelperColumn.MinRv) | ||
| val maxRv = getAttribute(input, HelperColumn.MaxRv) | ||
| val rvCnt = getAttribute(input, HelperColumn.RvCnt) | ||
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| val isCarryoverPair = And( | ||
| And(EqualTo(delCnt, Literal(1L)), EqualTo(insCnt, Literal(1L))), | ||
| And(EqualTo(rvCnt, Literal(2L)), EqualTo(minRv, maxRv))) | ||
| Filter(Not(isCarryoverPair), input) | ||
| } | ||
|
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| /** | ||
| * Adds a Project node that rewrites `_change_type` to `update_preimage` / | ||
| * `update_postimage` whenever a delete+insert pair is present in the partition. | ||
| * Expects the input to expose `_del_cnt` and `_ins_cnt`. | ||
| */ | ||
| private def addUpdateRelabelProjection(input: LogicalPlan): LogicalPlan = { | ||
| val changeTypeAttr = getAttribute(input, "_change_type") | ||
| val delCnt = getAttribute(input, HelperColumn.DelCnt) | ||
| val insCnt = getAttribute(input, HelperColumn.InsCnt) | ||
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| val isUpdate = And( | ||
| EqualTo(delCnt, Literal(1L)), | ||
| EqualTo(insCnt, Literal(1L))) | ||
| val isInvalid = Or(GreaterThan(delCnt, Literal(1L)), GreaterThan(insCnt, Literal(1L))) | ||
| val updateType = If(EqualTo(changeTypeAttr, Literal(Changelog.CHANGE_TYPE_INSERT)), | ||
| Literal(Changelog.CHANGE_TYPE_UPDATE_POSTIMAGE), | ||
| Literal(Changelog.CHANGE_TYPE_UPDATE_PREIMAGE)) | ||
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| val raiseInvalid = RaiseError( | ||
| Literal("CHANGELOG_CONTRACT_VIOLATION.UNEXPECTED_MULTIPLE_CHANGES_PER_ROW_VERSION"), | ||
| CreateMap(Nil), | ||
| StringType) | ||
| val caseExpr = CaseWhen(Seq(isInvalid -> raiseInvalid, isUpdate -> updateType), changeTypeAttr) | ||
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| val projectList = input.output.map { attr => | ||
| if (attr.name == "_change_type") Alias(caseExpr, "_change_type")() | ||
| else attr | ||
| } | ||
| Project(projectList, input) | ||
| } | ||
|
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| // --------------------------------------------------------------------------- | ||
| // Net Change Computation | ||
| // --------------------------------------------------------------------------- | ||
|
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| /** | ||
| * Collapses multiple changes per row identity into the net effect. | ||
| * Not yet implemented. | ||
| */ | ||
| private def injectNetChangeComputation( | ||
| plan: LogicalPlan, | ||
| cl: Changelog): LogicalPlan = { | ||
| plan | ||
| } | ||
|
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| // --------------------------------------------------------------------------- | ||
| // Helpers | ||
| // --------------------------------------------------------------------------- | ||
|
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| /** | ||
| * Removes any helper columns (see [[HelperColumn]]) that earlier steps added to the | ||
| * plan. Helper columns not present in the input are silently ignored, so this method | ||
| * can be applied unconditionally regardless of which post-processing steps ran. | ||
| */ | ||
| private def removeHelperColumns(input: LogicalPlan): LogicalPlan = { | ||
| Project(input.output.filterNot(a => HelperColumn.all.contains(a.name)), input) | ||
| } | ||
|
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| /** | ||
| * Looks up an attribute by name in a plan's output. Throws a clear error if missing -- | ||
| * used for required columns like `_change_type` / `_commit_version` / helper columns | ||
| * added by earlier steps; a missing column is always a programming error. | ||
| */ | ||
| private def getAttribute(plan: LogicalPlan, name: String): Attribute = | ||
| plan.output.find(_.name == name).getOrElse( | ||
| throw new IllegalStateException( | ||
| s"Required column '$name' not found in plan output: " + | ||
| plan.output.map(_.name).mkString(", "))) | ||
| } | ||
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