Github user nsyca commented on a diff in the pull request:
https://github.com/apache/spark/pull/16954#discussion_r103461455
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
---
@@ -707,13 +709,85 @@ class Analyzer(
} transformUp {
case other => other transformExpressions {
case a: Attribute =>
-
attributeRewrites.get(a).getOrElse(a).withQualifier(a.qualifier)
+ dedupAttr(a, attributeRewrites)
+ case s: SubqueryExpression =>
+ s.withNewPlan(dedupOuterReferencesInSubquery(s.plan,
attributeRewrites))
}
}
newRight
}
}
+ private def dedupAttr(attr: Attribute, attrMap:
AttributeMap[Attribute]): Attribute = {
+ attrMap.get(attr).getOrElse(attr).withQualifier(attr.qualifier)
+ }
+
+ /**
+ * The outer plan may have been de-duplicated and the function below
updates the
+ * outer references to refer to the de-duplicated attributes.
+ *
+ * For example (SQL):
+ * {{{
+ * SELECT * FROM t1
+ * WHERE EXISTS (SELECT 1
+ * FROM t2
+ * WHERE t1.c1 = t2.c1)
+ * INTERSECT
+ * SELECT * FROM t1
+ * WHERE EXISTS (SELECT 1
+ * FROM t2
+ * WHERE t1.c1 = t2.c1)
+ * }}}
+ * Plan before resolveReference rule.
--- End diff --
@dilipbiswal You probably are already on the right track that one of the
subquery expression is not required. I guess either `T1 intersect T1 where
exists (T2)` or a self-join scenario like `T1, T1 Tx where exists (T2 where
<Q>.col = T2.col)` with `<Q>` be `T1` or `Tx` should also do.
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