Github user mgaido91 commented on a diff in the pull request:
https://github.com/apache/spark/pull/19728#discussion_r150579715
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala
---
@@ -126,18 +143,41 @@ case class ConcatWs(children: Seq[Expression])
// All children are strings. In that case we can construct a fixed
size array.
val evals = children.map(_.genCode(ctx))
- val inputs = evals.map { eval =>
- s"${eval.isNull} ? (UTF8String) null : ${eval.value}"
- }.mkString(", ")
-
- ev.copy(evals.map(_.code).mkString("\n") + s"""
- UTF8String ${ev.value} = UTF8String.concatWs($inputs);
+ val argNums = evals.length
--- End diff --
no, I am saying the opposite. Let's consider an example, maybe I better can
explain what I mean in this way. Let's assume that we are running
`concat_ws(',', 'a', 'b')`. Then, `evals` would contain 3 elements. So here
your `argNums` would be 3. But
[here](https://github.com/apache/spark/pull/19728/files/e6b73abf33216fe564ee59213877403cf137c3b4#diff-2eb730f0723800778689468764627032R149)
you would be using only `$args[0]` and `$args[1]`, because the first element
(`','`, the separator) is handled differently.
Thus, I would suggest to have something like:
```
val sep = evals.head
val strings = evals.tail
val argNums = strings.length // note that this is evals.length -1
...
```
I think that in this way the code would be much clearer (other than fixing
this little bug).
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