John Gray <jgray@azuli.co.uk> writes:
> Please correct me if I've got this wrong, but it appears from the SRF
> API, that a SRF cannot readily refer to the TupleDesc to which it is
> expected to conform (i.e. the TupleDesc derived from the FROM clause of
> an original SELECT statement) because that is held in the executor state
> and not copied or linked into the function context.
> The reason I'm interested (and this might be a crazy idea) is that a
> function might choose to adapt its output based on what it is asked for.
Seems like a cool idea.
We could fairly readily add a field to ReturnSetInfo, but that would
only be available to functions defined as returning a set. That'd
probably cover most useful cases but it still seems a bit unclean.
I suppose that ExecMakeTableFunctionResult could be changed to *always*
pass ReturnSetInfo, even if it's not expecting the function to return
a set. That seems even less clean; but it would work, at least in the
current implementation.
Anyone have a better idea?
regards, tom lane