[postgis-users] Trace network from each source node and check that the trace reaches the sea

Stephen V. Mather svm at clevelandmetroparks.com
Thu Dec 30 15:28:50 PST 2021

Hi David,

This is a good example. I have modified this to walk networks before, 
and it's a minimal and understandable example:


There may be some better ways to do this, as the postgres tooling has 
changed quite a bit. The use of a function may be precluded by some 
modern fancy join type. Others can speak better to that than I can these 

Also, if you don't mind installing one more thing, pgrouting will do 
network traversal much more efficiently than a /WITH RECURSIVE/ network 





On 12/30/21 4:13 PM, Shaozhong SHI wrote:
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> In hydrological network, how to trace network from each source node 
> and check whether the trace can reach the sea?
> Any examples?
> Regards,
> David
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