Bruce Momjian <pgman@candle.pha.pa.us> writes:
> When we considered outervar1 as a constant, we could do the aggregate in
> the subquery using computations, but when SUM(outervar1) is computed in
> an above query, combining that with anything that is part of different
> query level makes no sense to me because those variables might not even
> exist at the level that aggregate is being computed.
Sure they will. They can only be outer (up-level) references, else the
parser would not have resolved them in the first place.
If you accept that SUM(localvar + outervar) is a sensible computation,
then I think you must accept that SUM(outervar1 + outervar2) makes sense
too. It's actually the exact same computation, it's just being
referenced from within a sub-query.
regards, tom lane