[pgrouting-users] Empty tuple from pgr_dijkstra

[Stephen Woodbridge]

On 2/19/2015 3:48 AM, Luís de Sousa wrote:
> Hi everyone,
>
> In a network with some 50 000 nodes, pgr_dijkstra is returning an
> empty tuple for about 7-8% of the nodes. Under exactly which
> conditions is pgr_dijkstra returning this result?

Probably it is not able to find a route between you start and end node.
This can happen if you data is not properly noded or you have 
disconnected sub graphs like an island with not bridge connecting to to 
the main network, etc.

-Steve