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Subject: Re: Null literals in AggregateReduceFunctionsRule
From: Julian Hyde <jhyde@apache.org>
In-Reply-To: <AM4PR03MB14104B2DD50FA8B79935830C8D4C0@AM4PR03MB1410.eurprd03.prod.outlook.com>
Date: Mon, 6 Feb 2017 17:04:57 -0800
Cc: Timo Walther <twalthr@apache.org>
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To: dev@calcite.apache.org
archived-at: Tue, 07 Feb 2017 01:05:13 -0000

Adding a cast around the null literal makes sense. I would use =
=E2=80=9CrexBuilder.makeCast(type, constantNull())=E2=80=9D rather than =
=E2=80=9CrexBuilder.makeNullLiteral(type.getSqlTypeName())=E2=80=9D =
because there=E2=80=99s a chance that the type needs precision & scale.

Can you please create a Calcite jira case and submit a pull request?

And by the way, I think I see similar patterns in =
AggregateExpandDistinctAggregatesRule, AggregateValuesRule and even =
RexBuilder.makeOver.

Julian


> On Feb 2, 2017, at 12:57 AM, Anton Mushin <Anton_Mushin@epam.com> =
wrote:
>=20
> Hello community,
> I have worked for support  standard deviation/variance functions in =
Flink SQL [1] and I got exception " Type NULL is not supported. Null =
values must have a supported type.".=20
> I started search root cause and found what problem come up from =
AggregateReduceFunctionsRule[2].  @twalthr confirmed it after[3].
>=20
> Now I have been used WA - the copy AggregateReduceFunctionsRule inside =
Flink with changes.
> Could we resolve the problem some way?
> I look forward to your reply.
>=20
> [1] https://issues.apache.org/jira/browse/FLINK-4604#
> [2] =
https://issues.apache.org/jira/browse/FLINK-4604?focusedCommentId=3D156152=
80&page=3Dcom.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=
#comment-15615280
> [3] =
https://issues.apache.org/jira/browse/FLINK-4604?focusedCommentId=3D156676=
97&page=3Dcom.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=
#comment-15667697
>=20
> Regards,
> Anton Mushin
>=20