Problem:
Select list should be non const when from list have tables or multiple tuples. Or upper query will regard wrong of isConstant
And make wrong constant folding
For example： when using nullif funtion with subquery which result in two alternative constant, planner would treat it as constant expr. So analyzer would report an error of order by clause can not be constant
Solusion:
Change inline view output to non constant, because (select 1 a from table) as view , a in output is no constant when we see
view.a outside
0c3acfdb7c