[FLINK-2115] TableAPI throws ExpressionException for "Dangling GroupBy operation"

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.9
• Fix Version/s: 1.0.0
• Component/s: Table SQL / API
• Assignee: Chengxiang Li
• Reporter: Fabian Hueske
• Created: 29/May/15 14:49
• Updated: 03/Dec/15 02:35
• Resolved: 02/Dec/15 11:23

Description

The following program below throws an ExpressionException due to a "Dangling GroupBy operation".
However, I think the program is semantically correct and should execute.

public static void main(String[] args) throws Exception {

  ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

  DataSet<Integer> data = env.fromElements(1,2,2,3,3,3,4,4,4,4);
  DataSet<Tuple2<Integer, Integer>> tuples = data
      .map(new MapFunction<Integer, Tuple2<Integer, Integer>>() {
        @Override
        public Tuple2<Integer, Integer> map(Integer i) throws Exception {
          return new Tuple2<Integer, Integer>(i, i*2);
        }
      });

  TableEnvironment tEnv = new TableEnvironment();
  Table t = tEnv.toTable(tuples).as("i, i2")
      .groupBy("i, i2").select("i, i2")
      .groupBy("i").select("i, i.count as cnt");

  tEnv.toSet(t, Row.class).print();
}