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Julian Hyde commented on CALCITE-6020: -------------------------------------- I regard SUM0 as a more fundamental operation than SUM - it matches the "+" operator in algebra, for instance - and suspect that we should use it whenever applicable. {{AggregateReduceFunctionsRule}} doesn't seem to be a good place for this logic to live. AggregateReduceFunctionsRule matches an {{Aggregate}}, and window functions never occur in an Aggregate. Maybe we also need a {{WindowReduceFunctionsRule}} (because window aggregates usually occur in a {{Window}} - although they also occur in a {{Project}}, at a different stage of planning). And then move the logic for particular window/aggregate functions to a neutral location (where whether-this-function-is-applied-to-a-window or whether-this-function-is-applied-to-a-group-that-may-be-empty are part of the context of the rewrite). > 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)