Eric Schwarzenbach <subscriber(at)blackbrook(dot)org> writes:
> I'm wondering whether columns, in the select list of a view that is used
> in a join, which are not used either as join criteria or in the select
> list of the overall query, effect the performance of the query.
If the view gets "flattened" into the calling query then unreferenced
columns will be optimized away, otherwise probably not. You haven't
given enough details about your intended view definition to be sure
whether it can be optimized, but if it's just a join it's fine.
regards, tom lane