Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3743#discussion_r112456485
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/table.scala
---
@@ -810,6 +810,47 @@ class Table(
new WindowedTable(this, window)
}
+ /**
+ * Groups the records of a table by assigning them to windows defined
by a time or row interval.
+ *
+ * For streaming tables of infinite size, grouping into windows is
required to define finite
+ * groups on which over-based aggregates can be computed.
+ *
+ * Over window for batch tables are currently not supported.
+ *
+ * @param overWindows windows that specifies how elements are grouped.
+ * @return Over windowed table
+ */
+ def window(overWindows: OverWindow*): OverWindowedTable = {
+
+ if (tableEnv.isInstanceOf[BatchTableEnvironment]) {
+ throw TableException("Over window for batch tables are currently not
supported.")
+ } else {
+ overWindows.foreach { overWindow =>
+ val orderName =
overWindow.orderBy.asInstanceOf[UnresolvedFieldReference].name
+ if (!orderName.equalsIgnoreCase("rowtime")
+ && !orderName.equalsIgnoreCase("proctime")) {
+ throw ValidationException(
+ s"OrderBy expression must be ['rowtime] or ['proctime], but
got ['${orderName}]")
+ }
+ }
+ }
+
+ if (overWindows.size != 1) {
+ throw TableException("OverWindow only supported single window at
current time.")
+ }
+
+ overWindows.foreach { overWindow =>
+ if (!overWindow.preceding.asInstanceOf[Literal].resultType.getClass
--- End diff --
This check should be done in `OverCall.validateInput()` as well.
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