[pgrouting-users] server closed the connection unexpectedly with shortest_path when using directed = true

[Stephen Woodbridge]

Charles Galpin wrote:
> Hi Steve
> 
> On May 17, 2010, at 11:03 AM, Stephen Woodbridge wrote:
>>
>> I do not think you should be passing -1 as the reverse cost, what is 
>> that supposed to mean? Edge weights should not be negative. If You are 
>> just trying to avoid it from taking a reverse edge for testing then 
>> set the value to a very large number instead.
> 
> I simply want to force the routing to not support traversing a link in 
> reverse (in other words force the routing to follow the only real world 
> path).  My links are directed (one way).
> 
> According to the following wiki page, a negative cost prevents an edge 
> from being inserted into the graph. 
> 
> http://pgrouting.postlbs.org/wiki/Dijkstra

OK, it has been a while since I read the docs, so maybe I should go read 
them again ;)

> I can see having a large number working by making the cost high, but 
> this doesn't seem right. 
> 
>>
>> Typically, you should be passing the column that contains the reverse 
>> cost and not a constant. In you example above "length" is a column 
>> that contains the cost, if your cost and reverse cost are the same and 
>> you just want to test a bidirectional graph then you could set you 
>> reverse cost to "length" also, like:
>>
>> SELECT gid AS id, source::integer,target::integer, length::double
>> precision AS cost, length::double precision as reverse_cost FROM links
> 
> Doesn't this just say my links are bidirectional and the cost is the 
> same? 

Yes

> This is exactly what I don't want :)

> Thanks,
> charles