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

[Imre Samu]

> 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
> _______________________________________________
> postgis-users mailing list
> postgis-users at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/postgis-users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20230717/a68c6f89/attachment.htm>