Paul Ramsey's original example was, I would guess, intended to be the
shortest, simplest example of using recursive functions. Adding more
complexity to the example will just make it harder to understand. It
was never intended to be the basis for a full solution and has a
fundamentally flawed architecture for that purpose; it confound toplogy
extraction with network walking.
I would suggest to the original poster that they switch over to
pg_routing which already has robust solutions to the problems they are
likely to encounter. In particular, the network walking algorithms use
the Boost Graph C++ library are likely to execute far faster than
anything which can be written in PL/pgSQL or python.
Ruven Brooks
On 5/8/2022 3:09 PM, Shaozhong SHI wrote:
Hi, Imre,
There is a possibility that the Walk the Network (Network Walking in
PostGIS · Paul Ramsey (cleverelephant.ca)
<http://blog.cleverelephant.ca/2010/07/network-walking-in-postgis.html?m=1&msclkid=5cf8409ecf0a11ecbbe2896397a25c2b>)
encountered more than 2 answers/outputs.
It may get confused and cannot finish.
Can we build something in the script to report these and should there
be an exception, allow it to complete the task?
Regards,
David
On Sun, 8 May 2022 at 00:59, Imre Samu <[email protected]> wrote:
Hi David,
> There is a loop of recursive query. It runs at a point where it
stops.
>Can anyone provide pointers how to solve this problem or work around?
Please share "this" recursive query;
My guess: Probably you have a "forever/endless loop" in your
data; *so you have to LIMIT the recursive part ;*
related links :
1.) with limiting "depth" ( wheredepth <1000 )
"Prevent infinite loop in recursive query in Postgresql"
https://stackoverflow.com/questions/51025607/prevent-infinite-loop-in-recursive-query-in-postgresql
2.) with LIMITING clause
https://www.cybertec-postgresql.com/en/recursive-queries-postgresql/
/"This example also demonstrates how an endless loop can be
avoided with a LIMIT clause on the parent query."/
Regards,
Imre
Shaozhong SHI <[email protected]> ezt írta (időpont: 2022.
máj. 7., Szo, 15:23):
There is a loop of recursive query. It runs at a point where
it stops.
This error turned up.- ERROR: invalid memory alloc request
size 1073741824
Can anyone provide pointers how to solve this problem or work
around?
Regards,
David
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