I am having some issues when using pgrouting's shortest path. I am following this tutorial available at http://workshop.pgrouting.org/chapters/shortest_path.html#dijkstra. This query returns a list of edges. Then I get the start and end points of each edge. Then I just join these points to show the shortest path. Just to let you know that I don't necessarily get the ending point of the first edge in the list to be the starting point of the second edge in the list returned. So I join, the ending and starting points of the two edges as well. However, sometimes the points are repeated and I have lines crossing over each other and the path looks a mess. What could be the reason behind this?