dongjoon-hyun commented on a change in pull request #28830: URL: https://github.com/apache/spark/pull/28830#discussion_r439907052
########## File path: sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala ########## @@ -2541,7 +2542,20 @@ class Dataset[T] private[sql]( def dropDuplicates(colNames: Seq[String]): Dataset[T] = withTypedPlan { val resolver = sparkSession.sessionState.analyzer.resolver val allColumns = queryExecution.analyzed.output - val groupCols = colNames.distinct.flatMap { (colName: String) => + // SPARK-31990: We must preserve the input order of `colNames` because of the compatibility + // issue (the Streaming's state store depends on the `groupCols` order). + val orderPreservingDistinctColNames = { + val nameSeen = mutable.Set[String]() Review comment: The reported issue claims that Scala `distinct` function was not enough. That's the reason why I asked that `Is there a change?` to fix Spark issue. As @HeartSaVioR 's commented (https://github.com/apache/spark/pull/28830#discussion_r439904302), we need a different code. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org