Github user viirya commented on a diff in the pull request:
https://github.com/apache/spark/pull/21240#discussion_r186276709
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/generators.scala
---
@@ -222,6 +222,51 @@ case class Stack(children: Seq[Expression]) extends
Generator {
}
}
+/**
+ * Replicate the row N times. N is specified as the first argument to the
function.
+ * {{{
+ * SELECT replicate_rows(2, "val1", "val2") ->
+ * 2 val1 val2
+ * 2 val1 val2
+ * }}}
+ */
+@ExpressionDescription(
+usage = "_FUNC_(n, expr1, ..., exprk) - Replicates `n`, `expr1`, ...,
`exprk` into `n` rows.",
--- End diff --
I checked the design doc for INTERSECT ALL and EXCEPT ALL. Looks like the
`n` is always stripped after Generate operation. So why we need to keep `n` in
`ReplicateRows` outputs? Can we do it like:
```
> SELECT _FUNC_(2, "val1", "val2");
val1 val2
val1 val2
```
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