I have a road network and I used pgr_createTopology and pgr_nodeNetwork to convert it for use in pgRouting library. However the results are fragmented and there is no continuous path. Furthermore I have to give source and target values instead of ID in the below query. here 747 and 311 are source and target values from table rather than IDs.

pgr_dijkstra(' SELECT id, source::int, target::int, length::double precision AS cost FROM guru_noded', 747, 311, false, false);

I am new to this.

2 Answers 2


Probabaly your "snapping tolerance" parameter did not match with the unit of your data, when you ran pgr_createTopology.

The dimension of the tolerance parameter depends on your data projection. Usually it’s either “degrees” or “meters”.

  • Are u saying that if I have my data in wgs84 lat long coordinate system, and run pgr_createtopology with tolerance parameter value 0.001, then 0.001 will be considered as degrees instead of meters? Commented Oct 27, 2020 at 18:35
  • Yes, this is correct. The snapping value is in the unit of your projection.
    – dkastl
    Commented Nov 13, 2020 at 12:27

have you tried another solution?

If you just want to calculate the faster or shorter path, just use the network analysis tool from QGIS


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