How A* Improves on Dijkstra (and When It Doesn't)

In my previous post on routing, I used Dijkstra&rsquo;s algorithm without much discussion of alternatives. The Dijkstra algorithm works for network routing, and for many problems it is the right choice. But pgRouting also ships with pgr_aStar , an implementation of the A* algorithm that can find the same shortest path while exploring fewer edges. The difference comes down to one thing: a heuristic…