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

Julian Hyde updated CALCITE-845:
--------------------------------
    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 [~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}

  was:
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 <[email protected]> Aug 11
"""
Postgres return type is "bigint for smallint or int arguments, numeric for 
bigint arguments, otherwise the same as the argument data type”[1]

SQL Server return type is int for tinyint, smallint or int; bigint for 
bigint[2].

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.
"""


> 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
>
> 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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