peter-toth commented on code in PR #34929:
URL: https://github.com/apache/spark/pull/34929#discussion_r852617516


##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CTESubstitution.scala:
##########
@@ -211,8 +212,33 @@ object CTESubstitution extends Rule[LogicalPlan] {
       } else {
         // A CTE definition might contain an inner CTE that has a higher 
priority, so traverse and
         // substitute CTE defined in `relation` first.
+        // NOTE: we must call `traverseAndSubstituteCTE` before 
`substituteCTE`, as the relations
+        // in the inner CTE have higher priority over the relations in the 
outer CTE when resolving
+        // inner CTE relations. For example:
+        // WITH t1 AS (SELECT 1)
+        // t2 AS (
+        //   WITH t1 AS (SELECT 2)
+        //   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) {

Review Comment:
   Oh I though you just made a typo and want to merge it 3.3+ only and maybe 
backport the bugfix parts to 3.2...



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