xuanyuanking commented on a change in pull request #27454: [SPARK-28228][SQL]
Change the default behavior for name conflict in nested WITH clause
URL: https://github.com/apache/spark/pull/27454#discussion_r376426416
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File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CTESubstitution.scala
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@@ -28,10 +29,49 @@ import
org.apache.spark.sql.internal.SQLConf.LEGACY_CTE_PRECEDENCE_ENABLED
*/
object CTESubstitution extends Rule[LogicalPlan] {
def apply(plan: LogicalPlan): LogicalPlan = {
- if (SQLConf.get.getConf(LEGACY_CTE_PRECEDENCE_ENABLED)) {
+ val isLegacy = SQLConf.get.getConf(LEGACY_CTE_PRECEDENCE_ENABLED)
+ if (isLegacy.isEmpty) {
+ assertNoNameConflictsInCTE(plan, inTraverse = false)
+ traverseAndSubstituteCTE(plan, inTraverse = false)
+ } else if (isLegacy.get) {
legacyTraverseAndSubstituteCTE(plan)
} else {
- traverseAndSubstituteCTE(plan, false)
+ traverseAndSubstituteCTE(plan, inTraverse = false)
+ }
+ }
+
+ /**
+ * Check the plan to be traversed has naming conflicts in nested CTE or not,
traverse through
+ * child, innerChildren and subquery for the current plan.
+ */
+ private def assertNoNameConflictsInCTE(
+ plan: LogicalPlan,
+ inTraverse: Boolean,
+ cteNames: Set[String] = Set.empty): Unit = {
+ plan.foreach {
+ case w @ With(child, relations) =>
+ val newNames = relations.map {
+ case (cteName, _) =>
+ if (cteNames.contains(cteName)) {
+ throw new AnalysisException(s"Name $cteName is conflict in
nested CTE. " +
+ s"Please set ${LEGACY_CTE_PRECEDENCE_ENABLED.key} to false so
that name defined " +
+ "in inner CTE takes precedence. See more details in
SPARK-28228.")
+ } else {
+ cteName
+ }
+ }.toSet
+ (w.innerChildren :+ child).foreach { p =>
Review comment:
Thanks for the detailed checking! Yes, that makes sense, we should only give
exception while legacy and non-legacy give different results. Done in 7249404
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