[SPARK-50598][SQL] An initial, no-op PR which adds new parameters to already existing classes UnresolvedWith, CTERelationRef and CTERelationDef to enable later implementation of recursive CTEs.

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

@@ -123,7 +123,7 @@ object CTESubstitution extends Rule[LogicalPlan] {
       startOfQuery: Boolean = true): Unit = {
     val resolver = conf.resolver
     plan match {
-      case UnresolvedWith(child, relations) =>
+      case UnresolvedWith(child, relations, _) =>
         val newNames = ArrayBuffer.empty[String]
         newNames ++= outerCTERelationNames
         relations.foreach {
@@ -149,7 +149,7 @@ object CTESubstitution extends Rule[LogicalPlan] {
       plan: LogicalPlan,
       cteDefs: ArrayBuffer[CTERelationDef]): LogicalPlan = {
     plan.resolveOperatorsUp {
-      case UnresolvedWith(child, relations) =>
+      case UnresolvedWith(child, relations, _) =>
         val resolvedCTERelations =
           resolveCTERelations(relations, isLegacy = true, forceInline = false, Seq.empty, cteDefs)
         substituteCTE(child, alwaysInline = true, resolvedCTERelations)
@@ -202,7 +202,7 @@ object CTESubstitution extends Rule[LogicalPlan] {
     var firstSubstituted: Option[LogicalPlan] = None
     val newPlan = plan.resolveOperatorsDownWithPruning(
         _.containsAnyPattern(UNRESOLVED_WITH, PLAN_EXPRESSION)) {
-      case UnresolvedWith(child: LogicalPlan, relations) =>
+      case UnresolvedWith(child: LogicalPlan, relations, _) =>
         val resolvedCTERelations =
           resolveCTERelations(relations, isLegacy = false, forceInline, outerCTEDefs, cteDefs) ++
             outerCTEDefs

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/PushdownPredicatesAndPruneColumnsForCTEDef.scala

@@ -122,7 +122,7 @@ object PushdownPredicatesAndPruneColumnsForCTEDef extends Rule[LogicalPlan] {
   private def pushdownPredicatesAndAttributes(
       plan: LogicalPlan,
       cteMap: CTEMap): LogicalPlan = plan.transformWithSubqueries {
-    case cteDef @ CTERelationDef(child, id, originalPlanWithPredicates, _) =>
+    case cteDef @ CTERelationDef(child, id, originalPlanWithPredicates, _, _, _) =>
       val (_, _, newPreds, newAttrSet) = cteMap(id)
       val originalPlan = originalPlanWithPredicates.map(_._1).getOrElse(child)
       val preds = originalPlanWithPredicates.map(_._2).getOrElse(Seq.empty)
@@ -141,7 +141,7 @@ object PushdownPredicatesAndPruneColumnsForCTEDef extends Rule[LogicalPlan] {
         cteDef
       }
 
-    case cteRef @ CTERelationRef(cteId, _, output, _, _) =>
+    case cteRef @ CTERelationRef(cteId, _, output, _, _, _) =>
       val (cteDef, _, _, newAttrSet) = cteMap(cteId)
       if (needsPruning(cteDef.child, newAttrSet)) {
         val indices = newAttrSet.toSeq.map(cteDef.output.indexOf)
@@ -170,7 +170,7 @@ object PushdownPredicatesAndPruneColumnsForCTEDef extends Rule[LogicalPlan] {
 object CleanUpTempCTEInfo extends Rule[LogicalPlan] {
   override def apply(plan: LogicalPlan): LogicalPlan =
     plan.transformWithPruning(_.containsPattern(CTE)) {
-      case cteDef @ CTERelationDef(_, _, Some(_), _) =>
+      case cteDef @ CTERelationDef(_, _, Some(_), _, _, _) =>
         cteDef.copy(originalPlanWithPredicates = None)
     }
 }

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala

@@ -801,10 +801,12 @@ object View {
  * @param child The final query of this CTE.
  * @param cteRelations A sequence of pair (alias, the CTE definition) that this CTE defined
  *                     Each CTE can see the base tables and the previously defined CTEs only.
+ * @param allowRecursion A boolean flag if recursion is allowed.
  */
 case class UnresolvedWith(
     child: LogicalPlan,
-    cteRelations: Seq[(String, SubqueryAlias)]) extends UnaryNode {
+    cteRelations: Seq[(String, SubqueryAlias)],
+    allowRecursion: Boolean = false) extends UnaryNode {
   final override val nodePatterns: Seq[TreePattern] = Seq(UNRESOLVED_WITH)
 
   override def output: Seq[Attribute] = child.output
@@ -830,12 +832,19 @@ case class UnresolvedWith(
  *                                   pushdown to help ensure rule idempotency.
  * @param underSubquery If true, it means we don't need to add a shuffle for this CTE relation as
  *                      subquery reuse will be applied to reuse CTE relation output.
+ * @param recursive If true, then this CTE Definition is recursive - it contains a self-reference.
+ * @param recursionAnchor A helper plan node that temporary stores the anchor term of recursive
+ *                        definitions. In the beginning of recursive resolution the `ResolveWithCTE`
+ *                        rule updates this parameter and once it is resolved the same rule resolves
+ *                        the recursive [[CTERelationRef]] references and removes this parameter.
  */
 case class CTERelationDef(
     child: LogicalPlan,
     id: Long = CTERelationDef.newId,
     originalPlanWithPredicates: Option[(LogicalPlan, Seq[Expression])] = None,
-    underSubquery: Boolean = false) extends UnaryNode {
+    underSubquery: Boolean = false,
+    recursive: Boolean = false,
+    recursionAnchor: Option[LogicalPlan] = None) extends UnaryNode {
 
   final override val nodePatterns: Seq[TreePattern] = Seq(CTE)
 
@@ -859,13 +868,15 @@ object CTERelationDef {
  *                             de-duplication.
  * @param statsOpt             The optional statistics inferred from the corresponding CTE
  *                             definition.
+ * @param recursive            If this is a recursive reference.
  */
 case class CTERelationRef(
     cteId: Long,
     _resolved: Boolean,
     override val output: Seq[Attribute],
     override val isStreaming: Boolean,
-    statsOpt: Option[Statistics] = None) extends LeafNode with MultiInstanceRelation {
+    statsOpt: Option[Statistics] = None,
+    recursive: Boolean = false) extends LeafNode with MultiInstanceRelation {
 
   final override val nodePatterns: Seq[TreePattern] = Seq(CTE)
 

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

@@ -4,13 +4,13 @@ CREATE TABLE cte_tbl USING csv AS WITH s AS (SELECT 42 AS col) SELECT * FROM s
 -- !query analysis
 CreateDataSourceTableAsSelectCommand `spark_catalog`.`default`.`cte_tbl`, ErrorIfExists, [col]
    +- WithCTE
-      :- CTERelationDef xxxx, false
+      :- CTERelationDef xxxx, false, false
       :  +- SubqueryAlias s
       :     +- Project [42 AS col#x]
       :        +- OneRowRelation
       +- Project [col#x]
          +- SubqueryAlias s
-            +- CTERelationRef xxxx, true, [col#x], false
+            +- CTERelationRef xxxx, true, [col#x], false, false
 
 
 -- !query
@@ -26,13 +26,13 @@ CREATE TEMPORARY VIEW cte_view AS WITH s AS (SELECT 42 AS col) SELECT * FROM s
 -- !query analysis
 CreateViewCommand `cte_view`, WITH s AS (SELECT 42 AS col) SELECT * FROM s, false, false, LocalTempView, UNSUPPORTED, true
    +- WithCTE
-      :- CTERelationDef xxxx, false
+      :- CTERelationDef xxxx, false, false
       :  +- SubqueryAlias s
       :     +- Project [42 AS col#x]
       :        +- OneRowRelation
       +- Project [col#x]
          +- SubqueryAlias s
-            +- CTERelationRef xxxx, true, [col#x], false
+            +- CTERelationRef xxxx, true, [col#x], false, false
 
 
 -- !query
@@ -43,13 +43,13 @@ Project [col#x]
    +- View (`cte_view`, [col#x])
       +- Project [cast(col#x as int) AS col#x]
          +- WithCTE
-            :- CTERelationDef xxxx, false
+            :- CTERelationDef xxxx, false, false
             :  +- SubqueryAlias s
             :     +- Project [42 AS col#x]
             :        +- OneRowRelation
             +- Project [col#x]
                +- SubqueryAlias s
-                  +- CTERelationRef xxxx, true, [col#x], false
+                  +- CTERelationRef xxxx, true, [col#x], false, false
 
 
 -- !query
@@ -58,13 +58,13 @@ INSERT INTO cte_tbl SELECT * FROM S
 -- !query analysis
 InsertIntoHadoopFsRelationCommand file:[not included in comparison]/{warehouse_dir}/cte_tbl, false, CSV, [path=file:[not included in comparison]/{warehouse_dir}/cte_tbl], Append, `spark_catalog`.`default`.`cte_tbl`, org.apache.spark.sql.execution.datasources.InMemoryFileIndex(file:[not included in comparison]/{warehouse_dir}/cte_tbl), [col]
 +- WithCTE
-   :- CTERelationDef xxxx, false
+   :- CTERelationDef xxxx, false, false
    :  +- SubqueryAlias s
    :     +- Project [43 AS col#x]
    :        +- OneRowRelation
    +- Project [col#x]
       +- SubqueryAlias S
-         +- CTERelationRef xxxx, true, [col#x], false
+         +- CTERelationRef xxxx, true, [col#x], false, false
 
 
 -- !query
@@ -80,13 +80,13 @@ INSERT INTO cte_tbl WITH s AS (SELECT 44 AS col) SELECT * FROM s
 -- !query analysis
 InsertIntoHadoopFsRelationCommand file:[not included in comparison]/{warehouse_dir}/cte_tbl, false, CSV, [path=file:[not included in comparison]/{warehouse_dir}/cte_tbl], Append, `spark_catalog`.`default`.`cte_tbl`, org.apache.spark.sql.execution.datasources.InMemoryFileIndex(file:[not included in comparison]/{warehouse_dir}/cte_tbl), [col]
 +- WithCTE
-   :- CTERelationDef xxxx, false
+   :- CTERelationDef xxxx, false, false
    :  +- SubqueryAlias s
    :     +- Project [44 AS col#x]
    :        +- OneRowRelation
    +- Project [col#x]
       +- SubqueryAlias s
-         +- CTERelationRef xxxx, true, [col#x], false
+         +- CTERelationRef xxxx, true, [col#x], false, false
 
 
 -- !query