Github user scwf commented on a diff in the pull request:
https://github.com/apache/spark/pull/5604#discussion_r29638526
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
---
@@ -529,6 +534,164 @@ class Analyzer(
makeGeneratorOutput(p.generator, p.generatorOutput), p.child)
}
}
+
+ object ResolveWindowFunction extends Rule[LogicalPlan] {
+ def hasWindowFunction(projectList: Seq[NamedExpression]): Boolean =
+ projectList.exists(hasWindowFunction)
+
+ def hasWindowFunction(expr: NamedExpression): Boolean = {
+ expr.find {
+ case window: WindowExpression => true
+ case _ => false
+ }.isDefined
+ }
+
+ /**
+ * From a Seq of [[NamedExpression]]s, extract window expressions and
+ * other regular expressions.
+ */
+ def extract(
+ expressions: Seq[NamedExpression]): (Seq[NamedExpression],
Seq[NamedExpression]) = {
+ val (windowExpressions, regularExpressions) =
expressions.partition(hasWindowFunction)
+ // Extract expressions which in windowExpressions but not in
regularExpressions.
+ val extractedExprBuffer = new ArrayBuffer[NamedExpression]()
+ def extractExpr(
+ expr: Expression): Expression = expr match {
+ case ne: NamedExpression =>
+ // If a named expression is not in regularExpressions, add iut
+ val missingExpr =
+ AttributeSet(Seq(expr)) -- (regularExpressions ++
extractedExprBuffer)
+ if (missingExpr.nonEmpty) {
+ extractedExprBuffer += ne
+ }
+ ne.toAttribute
+ case l: Literal => l // Do not use Alias to wrap a Literal.
--- End diff --
maybe case e: Expression if e.foldable => e
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