I saw this post：Routing issues with pgrouting, and try the ability of reverse_cost. As the result of this post, if there is only one way to go from one node to another, even though the reverse_cost ...
I use a river network on which has a lot of nodes to test pgRouting, and I run the SQL, searching for the shortest path between nodes. SELECT * FROM shortest_path(' SELECT gid as id, ...
I add a new column, naming it "reverse_cost", and give it the same data in the shape_leng column. But as I run the shortest path algorithm in pgadmin, I got an error message. here's my sql code ...