[DRILL-1180] Case messes up the datatype returned by function surrounding it - ASF JIRA

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Hit this while investigating tpch data variation between postgres and drill
Simplified tpch14 to the following query:

select
sum(case
when l.L_RETURNFLAG like 'R%'
then l.l_extendedprice * (1 - l.l_discount)
else 0
end)
from lineitem l;

returns bigint in the case of drill and double in the case of postgres. Extendedprice and discount are double though.

Drill:507996494
Postgres:507996454.406699

However when the case is removed and we use an equivalent filter instead drill and postgres return the same results:

select
sum(l.l_extendedprice * (1 - l.l_discount)
from lineitem l where l.L_RETURNFLAG like 'R%';

Postgres: 507996454.406699
Drill: 5.0799645440669966E8

This would explain the data mismatch for both TPCH14 and 8

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