[SPARK-38404][SQL][3.3] Improve CTE resolution when a nested CTE references an outer CTE

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CTESubstitution.scala

@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql.catalyst.analysis
 
-import scala.collection.mutable
+import scala.collection.mutable.ArrayBuffer
 
 import org.apache.spark.sql.catalyst.expressions.SubqueryExpression
 import org.apache.spark.sql.catalyst.plans.logical.{Command, CTERelationDef, CTERelationRef, InsertIntoDir, LogicalPlan, ParsedStatement, SubqueryAlias, UnresolvedWith, WithCTE}
@@ -55,27 +55,27 @@ object CTESubstitution extends Rule[LogicalPlan] {
       case _: Command | _: ParsedStatement | _: InsertIntoDir => true
       case _ => false
     }
-    val cteDefs = mutable.ArrayBuffer.empty[CTERelationDef]
+    val cteDefs = ArrayBuffer.empty[CTERelationDef]
     val (substituted, lastSubstituted) =
       LegacyBehaviorPolicy.withName(conf.getConf(LEGACY_CTE_PRECEDENCE_POLICY)) match {
         case LegacyBehaviorPolicy.EXCEPTION =>
           assertNoNameConflictsInCTE(plan)
-          traverseAndSubstituteCTE(plan, isCommand, cteDefs)
+          traverseAndSubstituteCTE(plan, isCommand, Seq.empty, cteDefs)
         case LegacyBehaviorPolicy.LEGACY =>
           (legacyTraverseAndSubstituteCTE(plan, cteDefs), None)
         case LegacyBehaviorPolicy.CORRECTED =>
-          traverseAndSubstituteCTE(plan, isCommand, cteDefs)
+          traverseAndSubstituteCTE(plan, isCommand, Seq.empty, cteDefs)
     }
     if (cteDefs.isEmpty) {
       substituted
     } else if (substituted eq lastSubstituted.get) {
-      WithCTE(substituted, cteDefs.sortBy(_.id).toSeq)
+      WithCTE(substituted, cteDefs.toSeq)
     } else {
       var done = false
       substituted.resolveOperatorsWithPruning(_ => !done) {
         case p if p eq lastSubstituted.get =>
           done = true
-          WithCTE(p, cteDefs.sortBy(_.id).toSeq)
+          WithCTE(p, cteDefs.toSeq)
       }
     }
   }
@@ -98,7 +98,7 @@ object CTESubstitution extends Rule[LogicalPlan] {
     val resolver = conf.resolver
     plan match {
       case UnresolvedWith(child, relations) =>
-        val newNames = mutable.ArrayBuffer.empty[String]
+        val newNames = ArrayBuffer.empty[String]
         newNames ++= outerCTERelationNames
         relations.foreach {
           case (name, relation) =>
@@ -121,11 +121,11 @@ object CTESubstitution extends Rule[LogicalPlan] {
 
   private def legacyTraverseAndSubstituteCTE(
       plan: LogicalPlan,
-      cteDefs: mutable.ArrayBuffer[CTERelationDef]): LogicalPlan = {
+      cteDefs: ArrayBuffer[CTERelationDef]): LogicalPlan = {
     plan.resolveOperatorsUp {
       case UnresolvedWith(child, relations) =>
         val resolvedCTERelations =
-          resolveCTERelations(relations, isLegacy = true, isCommand = false, cteDefs)
+          resolveCTERelations(relations, isLegacy = true, isCommand = false, Seq.empty, cteDefs)
         substituteCTE(child, alwaysInline = true, resolvedCTERelations)
     }
   }
@@ -170,21 +170,23 @@ object CTESubstitution extends Rule[LogicalPlan] {
    *     SELECT * FROM t
    *   )
    * @param plan the plan to be traversed
-   * @return the plan where CTE substitution is applied
+   * @param isCommand if this is a command
+   * @param outerCTEDefs already resolved outer CTE definitions with names
+   * @param cteDefs all accumulated CTE definitions
+   * @return the plan where CTE substitution is applied and optionally the last substituted `With`
+   *         where CTE definitions will be gathered to
    */
   private def traverseAndSubstituteCTE(
       plan: LogicalPlan,
       isCommand: Boolean,
-      cteDefs: mutable.ArrayBuffer[CTERelationDef]): (LogicalPlan, Option[LogicalPlan]) = {
+      outerCTEDefs: Seq[(String, CTERelationDef)],
+      cteDefs: ArrayBuffer[CTERelationDef]): (LogicalPlan, Option[LogicalPlan]) = {
     var lastSubstituted: Option[LogicalPlan] = None
     val newPlan = plan.resolveOperatorsUpWithPruning(
         _.containsAnyPattern(UNRESOLVED_WITH, PLAN_EXPRESSION)) {
       case UnresolvedWith(child: LogicalPlan, relations) =>
         val resolvedCTERelations =
-          resolveCTERelations(relations, isLegacy = false, isCommand, cteDefs)
-        if (!isCommand) {
-          cteDefs ++= resolvedCTERelations.map(_._2)
-        }
+          resolveCTERelations(relations, isLegacy = false, isCommand, outerCTEDefs, cteDefs)
         lastSubstituted = Some(substituteCTE(child, isCommand, resolvedCTERelations))
         lastSubstituted.get
 
@@ -200,10 +202,14 @@ object CTESubstitution extends Rule[LogicalPlan] {
       relations: Seq[(String, SubqueryAlias)],
       isLegacy: Boolean,
       isCommand: Boolean,
-      cteDefs: mutable.ArrayBuffer[CTERelationDef]): Seq[(String, CTERelationDef)] = {
-    val resolvedCTERelations = new mutable.ArrayBuffer[(String, CTERelationDef)](relations.size)
+      outerCTEDefs: Seq[(String, CTERelationDef)],
+      cteDefs: ArrayBuffer[CTERelationDef]): Seq[(String, CTERelationDef)] = {
+    var resolvedCTERelations = if (isLegacy || isCommand) {
+      Seq.empty
+    } else {
+      outerCTEDefs
+    }
     for ((name, relation) <- relations) {
-      val lastCTEDefCount = cteDefs.length
       val innerCTEResolved = if (isLegacy) {
         // In legacy mode, outer CTE relations take precedence. Here we don't resolve the inner
         // `With` nodes, later we will substitute `UnresolvedRelation`s with outer CTE relations.
@@ -221,31 +227,18 @@ object CTESubstitution extends Rule[LogicalPlan] {
         //   WITH t3 AS (SELECT * FROM t1)
         // )
         // t3 should resolve the t1 to `SELECT 2` instead of `SELECT 1`.
-        traverseAndSubstituteCTE(relation, isCommand, cteDefs)._1
-      }
-
-      if (cteDefs.length > lastCTEDefCount) {
-        // We have added more CTE relations to the `cteDefs` from the inner CTE, and these relations
-        // should also be substituted with `resolvedCTERelations` as inner CTE relation can refer to
-        // outer CTE relation. For example:
-        // WITH t1 AS (SELECT 1)
-        // t2 AS (
-        //   WITH t3 AS (SELECT * FROM t1)
-        // )
-        for (i <- lastCTEDefCount until cteDefs.length) {
-          val substituted =
-            substituteCTE(cteDefs(i).child, isLegacy || isCommand, resolvedCTERelations.toSeq)
-          cteDefs(i) = cteDefs(i).copy(child = substituted)
-        }
+        traverseAndSubstituteCTE(relation, isCommand, resolvedCTERelations, cteDefs)._1
       }
-
       // CTE definition can reference a previous one
-      val substituted =
-        substituteCTE(innerCTEResolved, isLegacy || isCommand, resolvedCTERelations.toSeq)
+      val substituted = substituteCTE(innerCTEResolved, isLegacy || isCommand, resolvedCTERelations)
       val cteRelation = CTERelationDef(substituted)
-      resolvedCTERelations += (name -> cteRelation)
+      if (!(isLegacy || isCommand)) {
+        cteDefs += cteRelation
+      }
+      // Prepending new CTEs makes sure that those have higher priority over outer ones.
+      resolvedCTERelations +:= (name -> cteRelation)
     }
-    resolvedCTERelations.toSeq
+    resolvedCTERelations
   }
 
   private def substituteCTE(

sql/core/src/test/resources/sql-tests/inputs/cte-nested.sql

@@ -135,4 +135,15 @@ WITH abc AS (SELECT 1)
 SELECT (
   WITH aBc AS (SELECT 2)
   SELECT * FROM aBC
-);
+);
+
+-- SPARK-38404: CTE in CTE definition references outer
+WITH
+  t1 AS (SELECT 1),
+  t2 AS (
+    WITH t3 AS (
+      SELECT * FROM t1
+    )
+    SELECT * FROM t3
+  )
+SELECT * FROM t2;

sql/core/src/test/resources/sql-tests/results/cte-legacy.sql.out

@@ -1,5 +1,5 @@
 -- Automatically generated by SQLQueryTestSuite
--- Number of queries: 16
+-- Number of queries: 17
 
 
 -- !query
@@ -219,3 +219,20 @@ SELECT (
 struct<scalarsubquery():int>
 -- !query output
 1
+
+
+-- !query
+WITH
+  t1 AS (SELECT 1),
+  t2 AS (
+    WITH t3 AS (
+      SELECT * FROM t1
+    )
+    SELECT * FROM t3
+  )
+SELECT * FROM t2
+-- !query schema
+struct<>
+-- !query output
+org.apache.spark.sql.AnalysisException
+Table or view not found: t1; line 5 pos 20

sql/core/src/test/resources/sql-tests/results/cte-nested.sql.out

@@ -1,5 +1,5 @@
 -- Automatically generated by SQLQueryTestSuite
--- Number of queries: 16
+-- Number of queries: 17
 
 
 -- !query
@@ -227,3 +227,19 @@ struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
 Name aBc is ambiguous in nested CTE. Please set spark.sql.legacy.ctePrecedencePolicy to CORRECTED so that name defined in inner CTE takes precedence. If set it to LEGACY, outer CTE definitions will take precedence. See more details in SPARK-28228.
+
+
+-- !query
+WITH
+  t1 AS (SELECT 1),
+  t2 AS (
+    WITH t3 AS (
+      SELECT * FROM t1
+    )
+    SELECT * FROM t3
+  )
+SELECT * FROM t2
+-- !query schema
+struct<1:int>
+-- !query output
+1

sql/core/src/test/resources/sql-tests/results/cte-nonlegacy.sql.out

@@ -1,5 +1,5 @@
 -- Automatically generated by SQLQueryTestSuite
--- Number of queries: 16
+-- Number of queries: 17
 
 
 -- !query
@@ -219,3 +219,19 @@ SELECT (
 struct<scalarsubquery():int>
 -- !query output
 2
+
+
+-- !query
+WITH
+  t1 AS (SELECT 1),
+  t2 AS (
+    WITH t3 AS (
+      SELECT * FROM t1
+    )
+    SELECT * FROM t3
+  )
+SELECT * FROM t2
+-- !query schema
+struct<1:int>
+-- !query output
+1