[postgis-users] best finding all paths with recursive query

[Imre Samu]

> How about finding out all possible route paths.?

I'm sorry, I don't fully understand your question as it could be
interpreted in several ways.
Could you provide a small set of test data and specify the kind of output
you're looking for?

Thanks,
  Imre

Shaozhong SHI <shishaozhong at gmail.com> ezt írta (időpont: 2023. júl. 17.,
H, 21:24):

> How about finding out all possible route paths.?
> Regards, david
>
> On Monday, 17 July 2023, Imre Samu <pella.samu at gmail.com> wrote:
>
>> > Which one is the best example for finding all paths with recursive
>> query?
>>
>> What type of graph are you working with?
>>
>> 1.)
>> You can check Yugabyte (PostgreSQL compatible) documentation for pure SQL
>> recursive-graph solutions for :
>> - Undirected cyclic graph
>> - Directed cyclic graph
>> - Directed acyclic graph
>> - Rooted tree
>> - Unique containing paths
>>
>> https://docs.yugabyte.com/preview/api/ysql/the-sql-language/with-clause/traversing-general-graphs/common-code/
>> I think there's a pretty good summary for solving basic graph problems
>> with SQL, which could potentially help you understand your problem as well
>> and find a solution for it...
>>
>> 2.)
>> Or use pgr_KSP - if you're only interested in the final result and you're
>> not attached to the purely recursive SQL solution.
>> And it's much more optimal for large graphs as well.
>> Here, you just need to provide a large enough K value (e.g., ~ maximum
>> (integer/bigint) value) and then you get all possible paths.
>> Or if you're only interested in the top 2, then set K=2.
>>
>> https://docs.pgrouting.org/latest/en/pgr_KSP.html
>> "The K shortest path routing algorithm based on Yen’s algorithm*. “K” is
>> the number of shortest paths desired.*"
>> https://en.wikipedia.org/wiki/K_shortest_path_routing
>>
>> regards,
>>  Imre
>>
>> Shaozhong SHI <shishaozhong at gmail.com> ezt írta (időpont: 2023. júl.
>> 17., H, 9:01):
>>
>>> Which one is the best example for finding all paths with recursive query?
>>>
>>> Regards,
>>>
>>> David
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