Re: Initialization of ResultTupleSlot in AppendNode

Amit Kapila <amit.kapila@huawei.com> writes:
> I observed that during initialization of planstate for Append Node, we
> allocate ResulttupleSlot, however it is used only to send NULL slot indicate
> no more tuples. 

> Is it right or there is any other purpose of it?

That also holds the plan's output tuple descriptor.  If you tried to
remove it, I think the ExecAssignResultTypeFromTL call would crash.
And if you removed *that*, upper nodes would get unhappy, cf
ExecGetResultType.

The use as an end-of-scan signal seems a bit vestigial, since we
could just as well return NULL, but it doesn't really cost enough
to be worth changing ...
        regards, tom lane