The sort keys under key, each {column, direction}, most significant
first. A column is kept exactly, '' included, for validation to judge; an
empty direction is malformed, as an empty join type is. A direction or an
entry key this version doesn't know could change the rows, so it makes the
node unreadable, once every entry has been read (PLAN §11.4). Shared by the
nodes that sort (Sort, Partition).
The sort keys under
key, each{column, direction}, most significant first. A column is kept exactly,''included, for validation to judge; an empty direction is malformed, as an empty join type is. A direction or an entry key this version doesn't know could change the rows, so it makes the node unreadable, once every entry has been read (PLAN §11.4). Shared by the nodes that sort (Sort, Partition).