Routable network from osm2pgsql schema

Question

I've import osm file into database by with this command:

osm2pgsql.exe -c -C 3000 -G -d OSM -U postgres --hstore -S default.style data.osm.pbf

After import I've add required columns:

ALTER TABLE planet_osm_line ADD COLUMN source INTEGER;
ALTER TABLE planet_osm_line ADD COLUMN target INTEGER;

and run pgr_createTopology function over this table:

select pgr_createTopology ('planet_osm_line', .001, 'way', 'osm_id');

Next I find out ids of nearest vertices from generated table planet_osm_line_vertices_pgr (for example vertices with ids 100 and 200) and apply them into routing function like this:

SELECT * FROM pgr_dijkstra('
SELECT osm_id AS id,
     source,
     target,
     st_length(way) AS cost
    FROM planet_osm_line',
100, 
200, 
directed := true)

But this give me nothing rows. Can you tell me what I do wrong?

Answer 1

First thing - run pgr_analyzeGraph function - as I think it'll tell you topology is incorrect..

Creating correct topology for pg_routing is not as simple as just running pgr_createTopology function - your data must be topologically correct before it, so you have to run pgr_nodeNetwork, but still it's not the best resolution.

It's much better to use topology created by some processors such as osm2pgrouting or osm2po. Last one is best (IMO)