Github user marmbrus commented on a diff in the pull request:
https://github.com/apache/spark/pull/1497#discussion_r15157732
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
---
@@ -152,6 +155,34 @@ class Analyzer(catalog: Catalog, registry:
FunctionRegistry, caseSensitive: Bool
}
/**
+ * This rule finds expressions in HAVING clause filters that depend on
+ * unresolved attributes. It pushes these expressions down to the
underlying
+ * aggregates and then projects them away above the filter.
+ */
+ object UnresolvedHavingClauseAttributes extends Rule[LogicalPlan] {
+ def apply(plan: LogicalPlan): LogicalPlan = plan transform {
+ case pl @ Filter(fexp, agg @ Aggregate(_, ae, _)) if
!fexp.childrenResolved => {
+ val alias = Alias(fexp, makeTmp())()
+ val aggExprs = Seq(alias) ++ ae
+
+ val newCond = EqualTo(Cast(alias.toAttribute, BooleanType),
Literal(true, BooleanType))
+
+ val newFilter = ResolveReferences(pl.copy(condition = newCond,
+ child = agg.copy(aggregateExpressions = aggExprs)))
+
+ Project(pl.output, newFilter)
+ }
+ }
+
+ private val curId = new java.util.concurrent.atomic.AtomicLong()
+
+ private def makeTmp() = {
+ val id = curId.getAndIncrement()
+ s"tmp_cond_$id"
--- End diff --
All `NamedExpression`s have a globally unique id (i.e. the `#number` in the
`toString`), so we can just create an Alias with a fixed `name`. I'd consider
naming it something like `havingCondition`.
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