Github user hequn8128 commented on a diff in the pull request: https://github.com/apache/flink/pull/3696#discussion_r111320841 --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/nodes/datastream/DataStreamCorrelate.scala --- @@ -36,14 +36,14 @@ import org.apache.flink.types.Row class DataStreamCorrelate( cluster: RelOptCluster, traitSet: RelTraitSet, - inputNode: RelNode, --- End diff -- hi, sorry for missing any commons about this fix. After decoration phase, the class type of inputNode is `HepRelVertex` and it will throws ClassCastException at `val inputDS = inputNode.asInstanceOf[DataStreamRel].translateToPlan(tableEnv)`. You can reproduce this exception by running tests in `DataStreamUserDefinedFunctionITCase`. The reason why there is no problems after runVolcanoPlanner is that `DataStreamCorrelateRule` does the transformation from `RelSubset` to `DataStreamRel`. I think it's better to override the `input` parameter and use `getInput` when translate to plan. What do you think, thx~
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