Github user hvanhovell commented on a diff in the pull request:
https://github.com/apache/spark/pull/9819#discussion_r47465844
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/windowExpressions.scala
---
@@ -246,85 +260,238 @@ object SpecifiedWindowFrame {
}
}
+case class UnresolvedWindowExpression(
+ child: Expression,
+ windowSpec: WindowSpecReference) extends UnaryExpression with
Unevaluable {
+
+ override def dataType: DataType = throw new UnresolvedException(this,
"dataType")
+ override def foldable: Boolean = throw new UnresolvedException(this,
"foldable")
+ override def nullable: Boolean = throw new UnresolvedException(this,
"nullable")
+ override lazy val resolved = false
+}
+
+case class WindowExpression(
+ windowFunction: Expression,
+ windowSpec: WindowSpecDefinition) extends Expression with Unevaluable {
+
+ override def children: Seq[Expression] = windowFunction :: windowSpec ::
Nil
+
+ override def dataType: DataType = windowFunction.dataType
+ override def foldable: Boolean = windowFunction.foldable
+ override def nullable: Boolean = windowFunction.nullable
+
+ override def toString: String = s"$windowFunction $windowSpec"
+}
+
/**
- * Every window function needs to maintain a output buffer for its output.
- * It should expect that for a n-row window frame, it will be called n
times
- * to retrieve value corresponding with these n rows.
+ * A window function is a function that can only be evaluated in the
context of a window operator.
*/
trait WindowFunction extends Expression {
- def init(): Unit
+ /** Frame in which the window operator must be executed. */
+ def frame: WindowFrame = UnspecifiedFrame
--- End diff --
It is a bit more strict than that. It is the only frame in which a
WindowFunction is supposed to be evaluated.
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
