Github user kaibozhou commented on a diff in the pull request: https://github.com/apache/flink/pull/4355#discussion_r135171980 --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/codegen/AggregationCodeGenerator.scala --- @@ -356,6 +486,9 @@ class AggregationCodeGenerator( """.stripMargin if (needMerge) { + if (accConfig != null && accConfig.isStateBackedDataViews) { + throw new CodeGenException("DataView doesn't support merge when the backend uses state.") --- End diff -- I found the exception will be throw in everywhere call generateAggregations(..). I think we can print funcName in exception info.
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