Another planner/optimizer question...

Once again, a slightly convoluted question, but it seems that PG may be
doing a little more work than is necessary when selecting from views with
sub-selects. It seems that every time a view field is being referenced in
an outer select expression, the view field is being re-evaluated. Is there
any way to get PG to know that it only needs to do the aggregate once?

eg.
  create table b(f1 int, f2 int);  create table r(f1 int);
  create view bv as select f1,f2,       exists(select * from r where r.f1=b.f1) as has_f1,       exists(select * from r
wherer.f1=b.f2) as has_f2  from b;
 
  explain select f1,f2,       case when has_f1 and has_f2 then 'both'             when has_f1 then 'f1_only'
when has_f2 then 'f2_only'             else 'none'        end as status   from bv;
 
   Seq Scan on b  (cost=0.00..20.00 rows=1000 width=8)     SubPlan       ->  Seq Scan on r  (cost=0.00..22.50 rows=5
width=4)      ->  Seq Scan on r  (cost=0.00..22.50 rows=5 width=4)       ->  Seq Scan on r  (cost=0.00..22.50 rows=5
width=4)      ->  Seq Scan on r  (cost=0.00..22.50 rows=5 width=4)
 


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