[GitHub] [spark] xuanyuanking commented on a change in pull request #28326: [SPARK-27340][SS] Alias on TimeWindow expression cause watermark metadata lost

[GitBox <gi...@apache.org>]

xuanyuanking commented on a change in pull request #28326:
URL: https://github.com/apache/spark/pull/28326#discussion_r416419173



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File path: sql/core/src/main/scala/org/apache/spark/sql/Column.scala
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@@ -1040,17 +1034,11 @@ class Column(val expr: Expression) extends Logging {
    *   df.select($"colA".name("colB"))
    * }}}
    *
-   * If the current column has metadata associated with it, this metadata will be propagated
-   * to the new column.  If this not desired, use `as` with explicitly empty metadata.

Review comment:
       These comments added together with the changes we just reverted. But it's good to have clear comments, I'll rephrase and add them back in the follow-up.




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