Re: make add_paths_to_append_rel aware of startup cost

What do you think about this in my last reply?  "If my above 

analysis is correct,  I think the best way to  handle this is if there 

is no more tables to join, we use cheapest  fraction cost for all 

the kinds of relations,  including plain relation,  append rel, 

subquery and so on, If we have more tables to join,  we use

cheapest startup cost.".  This is what is in my mind now.