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  1. Flink
  2. FLINK-4557 Table API Stream Aggregations
  3. FLINK-5990

Add [partitioned] event time OVER ROWS BETWEEN x PRECEDING aggregation to SQL

    Details

    • Type: Sub-task
    • Status: Closed
    • Priority: Major
    • Resolution: Implemented
    • Affects Version/s: None
    • Fix Version/s: 1.3.0
    • Component/s: Table API & SQL
    • Labels:
      None

      Description

      The goal of this issue is to add support for OVER ROWS aggregations on event time streams to the SQL interface.

      Queries similar to the following should be supported:

      SELECT 
        a, 
        SUM(b) OVER (PARTITION BY c ORDER BY rowTime() ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) AS sumB,
        MIN(b) OVER (PARTITION BY c ORDER BY rowTime() ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) AS minB
      FROM myStream
      

      The following restrictions should initially apply:

      • All OVER clauses in the same SELECT clause must be exactly the same.
      • The PARTITION BY clause is required
      • The ORDER BY clause may only have rowTime() as parameter. rowTime() is a parameterless scalar function that just indicates event time mode.
      • UNBOUNDED PRECEDING is not supported (see FLINK-5803)
      • FOLLOWING is not supported.

      The restrictions will be resolved in follow up issues. If we find that some of the restrictions are trivial to address, we can add the functionality in this issue as well.

      This issue includes:

      • Design of the DataStream operator to compute OVER ROW aggregates
      • Translation from Calcite's RelNode representation (LogicalProject with RexOver expression).

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              • Assignee:
                sunjincheng121 sunjincheng
                Reporter:
                sunjincheng121 sunjincheng
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                • Created:
                  Updated:
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