[postgis-users] Recursive query - ERROR: invalid memory alloc request size 1073741824

[Imre Samu]

> I am thinking of generating startnode and endnode values by using
St_startpoint(geom) and ST_endpoint(geom),
> Is this feasible?

if your input data is “noded” correctly - then YES ...
“noded” network =  at every intersection in your road/water network all the
edges will be broken into separate road/water segments.
And you have to assign the same "node id" for the same physical points.  (
ST_DWithin magic )

be careful:  The "Network Walking" example was a nodded network ( without
an intersection! )
maybe you can test the https://postgis.net/docs/CreateTopology.html
function also;

Imre


Shaozhong SHI <shishaozhong at gmail.com> ezt írta (időpont: 2022. máj. 8., V,
3:38):

> Testing shows that using startnode and endnode of id values of a line does
> lead to a fast completion of processing.
> However, at the moment, I am not sure whether these startnode (id values)
> and endnode (id values) are correct.
>
> I am thinking of generating startnode and endnode values by using
> St_startpoint(geom) and ST_endpoint(geom),
>
> And then try out your alternative method for recursive query to see
> whether walk the network works.
>
> Is this feasible?
>
> Regards,
>
> David
>
> On Sun, 8 May 2022 at 00:59, Imre Samu <pella.samu at gmail.com> 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"   ( where depth < 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 <shishaozhong at gmail.com> 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
>>> _______________________________________________
>>> postgis-users mailing list
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