Zoltan Haindrich created CALCITE-5953: -----------------------------------------
Summary: AggregateCaseToFilterRule may make inaccurate SUM transformation Key: CALCITE-5953 URL: https://issues.apache.org/jira/browse/CALCITE-5953 Project: Calcite Issue Type: Bug Reporter: Zoltan Haindrich Assignee: Zoltan Haindrich consider: `sum(case when x = 1 then 2 else 0 end) as b` notice that this expression may only be null if there are no rows in the table `AggregateCaseToFilterRule` rewrites the above expression to `sum(1) filter (where x=2)` which broadens when it could be `null` to when there are no matches to the filter * `A` is `0` correctly in this case; but I think it will be still `0` in case there are 0 input rows * The result for `B` supposed to be `0` but since there are no matches by the filter it becomes `null` * `C` is not touched ``` # Convert CASE to FILTER without matches select sum(case when x = 1 then 1 else 0 end) as a, sum(case when x = 1 then 2 else 0 end) as b, sum(case when x = 1 then 3 else -1 end) as c from (values 0, null, 0, 2) as t(x); +---+---+----+ | A | B | C | +---+---+----+ | 0 | 0 | -4 | +---+---+----+ (1 row) !ok EnumerableCalc(expr#0..2=[{inputs}], expr#3=[CAST($t0):INTEGER], A=[$t3], B=[$t1], C=[$t2]) EnumerableAggregate(group=[{}], A=[COUNT() FILTER $1], B=[SUM($2) FILTER $3], C=[SUM($0)]) EnumerableCalc(expr#0=[{inputs}], expr#1=[1], expr#2=[=($t0, $t1)], expr#3=[3], expr#4=[-1], expr#5=[CASE($t2, $t3, $t4)], expr#6=[IS TRUE($t2)], expr#7=[2], $f2=[$t5], $f3=[$t6], $f4=[$t7], $f5=[$t6]) EnumerableValues(tuples=[[{ 0 }, { null }, { 0 }, { 2 }]]) !plan ``` -- This message was sent by Atlassian Jira (v8.20.10#820010)