[
https://issues.apache.org/jira/browse/CALCITE-6020?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17873751#comment-17873751
]
Norman Jordan commented on CALCITE-6020:
----------------------------------------
I have played around with creating a new RelRule that looks at the project list
and converts SUM to SUM0 for an OVER clause. The Rule is only applied when the
project list contains an OVER clause with an SUM aggregate.
All of the tests pass except for SqlToRelConverterTests. The current change
converts SUM to SUM0 during planning so it is expected that the
SqlToRelConverterTests need to be updated.
SUM0 has value, but not everyone will want it. Some users find it necessary to
convert SUM0 back to SUM, so we want an easy way to disable the SUM to SUM0
conversion.
I'll post my code tomorrow as a proof of concept and see if we can work from
there.
> SqlToRelConverter should not replace windowed SUM with equivalent expression
> using SUM0
> ---------------------------------------------------------------------------------------
>
> Key: CALCITE-6020
> URL: https://issues.apache.org/jira/browse/CALCITE-6020
> Project: Calcite
> Issue Type: Improvement
> Reporter: Zoltan Haindrich
> Assignee: Zoltan Haindrich
> Priority: Major
> Labels: pull-request-available
>
> {{SqlToRelConverter}} replaces {{SUM}} with {{SUM0}} around
> [here|https://github.com/apache/calcite/blob/e1991e08a225ef08c2402ab35c310d88fff3c222/core/src/main/java/org/apache/calcite/sql2rel/SqlToRelConverter.java#L5885]
> This might have been needed at some point in the past - but I think it will
> be better to leave it as {{SUM}} - as in case there is no {{SUM0}} in the
> system that will be replaced with a {{COALESCE(SUM(...) , 0 )}} to provide it
> - as see
> [here|https://github.com/apache/calcite/blob/e1991e08a225ef08c2402ab35c310d88fff3c222/core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java#L1288]
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
