Fix failed in regression_test/suites/query_p0/group_concat/test_group_concat.groovy
select
group_concat( distinct b1, '?'), group_concat( distinct b3, '?')
from
table_group_concat
group by
b2
exception:
lowestCostPlans with physicalProperties(GATHER) doesn't exist in root group
The root cause is '?' is push down to slot by NormalizeAggregate, AggregateStrategies treat the slot as a distinct parameter and generate a invalid PhysicalHashAggregate, and then reject by ChildOutputPropertyDeriver.
I fix this bug by avoid push down literal to slot in NormalizeAggregate, and forbidden generate stream aggregate node when group by slots is empty
cc363f26c2