Hi team, Recently I am trying to explore the new features of Flink 1.12 with Batch Execution.
I locally wrote a classic WordCount program to read from text file and count the words (almost same as the one in Flink Github repo https://github.com/apache/flink/blob/master/flink-examples/flink-examples-streaming/src/main/scala/org/apache/flink/streaming/scala/examples/wordcount/WordCount.scala), and after reading https://ci.apache.org/projects/flink/flink-docs-release-1.12/dev/datastream_execution_mode.html I added `env.setRuntimeMode(RuntimeExecutionMode.BATCH);` after declare the "env" to make it execute under BATCH mode. After running the code, the printed results showed only final count results instead of incremental results, which is expected. *But I also notice, all the words that only appear once have NOT been printed out*. I have tried different things like wrap the word in a case class etc, and read more details and see if I have missed anything but still not able to figure out (And I have tried the default examples come with the Flink package and got same results, and with using DataSet API I do not see this issue). Is there anything extra user need to specify or notice when using BATCH execution mode in datastream API with Flink 1.12 or this is kind of a bug please? The flink version I used is 1.12 with scala 2.11 (also tried java 1.8 and observed same issue) Please let me know if you need other info to help diagnose. Thank you very much! Bests, Derek Sheng
