NikhilS <nikkhils@gmail.com> writes: > To allow both of the above to hold, I think the subselect will have to be > treated like a EXPR_SUBLINK subquery. I was wondering if we have a similar > mechanism for plain selects/subselects to check and restrict their output to > a single row.
No. Offhand I think you'd either need to relax EXPR_SUBLINK to allow multiple output columns, or invent a ROW_SUBLINK SubLinkType that is just like EXPR_SUBLINK except for allowing multiple output columns. The latter would probably be less likely to break other things...
Yeah, was looking at EXPR_SUBLINK and its single column use case and drove to the same conclusion that inventing a new sublink type would be better too. It is indeed becoming a "not so simple and narrow fix" as you had mentioned earlier in your first response :)
