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  1. Calcite
  2. CALCITE-845

Derive SUM’s return type by a customizable policy

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 1.5.0
    • Component/s: None
    • Labels:

      Description

      The purpose is to return correct sum result when the number goes beyond its type limitation. Currently Calcite behaves "type sum( x ) = type x", so if the sum overflows, user get negative result.

      Traditional SQL engines all expand the sum return type though in different ways.

      From Julian Hyde, Aug 11:

      Postgres return type is "bigint for smallint or int arguments, numeric for bigint arguments, otherwise the same as the argument data type” [ http://docs.oracle.com/database/121/SQLRF/functions196.htm#i89126 ]

      SQL Server return type is int for tinyint, smallint or int; bigint for bigint [ http://public.dhe.ibm.com/ps/products/db2/info/vr101/pdf/en_US/DB2SQLRefVol1-db2s1e1011.pdf ].

      I can see your point that “User demands the correct sum result”. But I’d also be pissed with Postgres if it returned a numeric (arbitrary precision) result when I am summing a bigint value. So I don’t think we’re going to please everyone.

      I think the solution is to add the policy to derive SUM’s return type to as a new method to RelDataTypeSystem. Then Kylin can supply its own.

        Attachments

        1. CALCITE-845_2.patch
          9 kB
          Maryann Xue
        2. CALCITE-845.patch
          10 kB
          Maryann Xue

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            People

            • Assignee:
              julianhyde Julian Hyde
              Reporter:
              liyang.gmt8@gmail.com liyang
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              Dates

              • Created:
                Updated:
                Resolved: