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  1. Calcite
  2. CALCITE-695

Do not add SINGLE_VALUE aggregate function to a sub-query that will never return more than one row

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 1.3.0-incubating
    • Fix Version/s: 1.3.0-incubating
    • Component/s: None
    • Labels:
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      Description

      In the following query, the subquery is producing a scalar value but the logical plan still creates a SqlSingleValueAggFunction.

      select r_regionkey from region
         where r_regionkey > (select min(n_regionkey) * 2 from nation);
      

      If the aggregate is just min(n_regionkey) instead of the expression min(n_regionkey) * 2 then no SqlSingleValueAggFunction is created. Ideally, both should behave the same.

      This is not necessarily a bug but it does create a burden on the underlying execution engine to support this function even in cases where it may not be needed.

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            • Assignee:
              julianhyde Julian Hyde
              Reporter:
              amansinha100 Aman Sinha
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              • Created:
                Updated:
                Resolved: