To have a routable set of roads in a database and to have a software that can calculate the shortest path (e.g. simple Dijkstra) through this set in a reasonable amount of time (up to 2 seconds). Required to be usable in the real world by real vehicles.
I have written a few parsers to parse .osm nodes and edges into a MySQL database. Then I applied a Java application that loads all the nodes and edges into memory, creates a graph from those and does a Dijkstra's algorithm routing on it. I am satisfied with the speed that it has.
Recently I found out that Openstreetmap project has switched from MySQL to PostgreSQL.
Then I found the pgRouting project.
I was impressed by the possible advantages:
- it can take traffic lights into account;
- it can take crossings into account;
- it can take signs and restrictions into account;
- it even can take slopes into account!
- it can take turn restrictions into account;
- it even promises to take weather conditions into account.
So the questions are:
- Are all those advantages real?
- Isn't pgRouting a kind of a blackbox? There are just a few tutorials on how to use it, and even these tutorials introduce even more unanswered questions. Isn't it simpler to build the desired [Goal] system from scratch?
- What's the whole purpose of storing routable data the PostgreSQL/PostGIS way (geometry columns, strange database schema) instead of having just two tables - nodes and edges in a simple MySQL database?