hemanthboyina commented on code in PR #58666:
URL: https://github.com/apache/spark/pull/58666#discussion_r4048931529


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sql/catalyst/src/main/scala/org/apache/spark/sql/execution/datasources/v2/DataSourceV2Relation.scala:
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@@ -602,11 +604,23 @@ object DataSourceV2Relation {
 
         val catalystColStat = ColumnStat(distinct, min, max, nullCount, 
avgLen, maxLen, histogram)
 
-        output.foreach(attribute => {
-          if (attribute.name.equals(key.describe())) {
-            colStats = colStats :+ (attribute -> catalystColStat)
+        // Catalyst statistics are keyed by top-level Attribute, so only 
single-part references
+        // can be matched to an output column.
+        val fieldNames = key.fieldNames
+        if (fieldNames.length == 1) {
+          val fieldName = fieldNames.head
+          val matches = output.filter(attribute => resolver(attribute.name, 
fieldName))
+          // On an ambiguous case-insensitive match (e.g. outputs "id" and 
"ID"), require a unique
+          // exact-name match, otherwise skip so CBO is not fed the wrong 
column.
+          val matched = matches match {

Review Comment:
   Right, the retained stat was traversal-order dependent. Now grouping matches 
by output attribute (exprId) and preferring the exact-name key,  skipping when 
it's still ambiguous, so the result is deterministic. Added a regression test 
for the many-keys-to-one-output case.



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