[jira] [Updated] (CALCITE-845) Derive SUM’s return type by a customizable policy

["Maryann Xue (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-845?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Maryann Xue updated CALCITE-845:
--------------------------------
    Attachment: CALCITE-845.patch

Thanks, [~julianhyde]! I got SUM working in Phoenix/Calcite with this change. Could you please review the patch?

> Derive SUM’s return type by a customizable policy
> -------------------------------------------------
>
>                 Key: CALCITE-845
>                 URL: https://issues.apache.org/jira/browse/CALCITE-845
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: liyang
>            Assignee: Julian Hyde
>              Labels: Phoenix
>         Attachments: CALCITE-845.patch
>
>
> 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 [~julianhyde], Aug 11:
> {quote}
> 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.
> {quote}



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