Amit Kapila <amit.kap...@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 -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers