[pgrouting-users] select multiple shortest paths from one to several points

Nate Wessel bike756 at gmail.com
Thu Jul 18 10:45:19 PDT 2013

I'm looking to select a number of shortest paths from one point to each 
of a set of points. For example, I would like to generate paths from my 
house to every coffee shop in the metro area.

Conceptually, it seems like this should be a simple problem, but I'm 
running into issues when I try to construct a query to actually do it. I 
managed to get as far as getting a nearest-network-node ID for each of 
my coffee shops into a table by themselves.

 From that point, I get a little lost. As far as I can tell, I have 
three tables to join together somehow: The network edges table, the 
table with the destination node IDs, and the table that results from a 
shortest path query. It's simple enough to join the network edge table 
geometry to the result of a single path query. But how do I pass a 
variable from my node IDs table to the end-point parameter of a 
shortest-path function?

When I tried something like:

FROM destination_nodes, shortest_path(..., network_nodes.id ,...)

JOIN network_edges ON ....

I get an error saying I can't pass a variable from the same query level 
to the function.

Can someone please help me understand how I need to structure this query 
to get the geometry of the paths associated with information from my 
destination_nodes table?

Much thanks,

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