[
https://issues.apache.org/jira/browse/CALCITE-6020?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17876120#comment-17876120
]
Norman Jordan commented on CALCITE-6020:
----------------------------------------
You are correct that SUM0 will never produce a NULL result, but SUM could. This
is one of the big reasons why SUM0 would get used.
Did the query go through planning? Did the planner include the rule
{*}CoreRules.PROJECT_OVER_SUM_TO_SUM0_RULE{*}?
> 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: Norman Jordan
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.38.0
>
>
> {{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)
