Hitoshi Harada <umi.tan...@gmail.com> writes: > I wonder why SortState is a ScanState. As far as I know ScanState > means the node may need projection and/or qualification, or it scans > some relation, but Sort actually doesn't do such things.
No, not really. Per the comment for ScanState: * ScanState extends PlanState for node types that represent * scans of an underlying relation. It can also be used for nodes * that scan the output of an underlying plan node --- in that case, * only ScanTupleSlot is actually useful, and it refers to the tuple * retrieved from the subplan. It might be that we don't actually need ScanTupleSlot right now in the implementation of Sort, but I don't see a good reason to remove the field. We might just have to put it back later. BTW, Sort is not the only node type like this --- I see at least Material that's not projection-capable but has a ScanState. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers