[pgrouting-users] pgRouting Memory Issues

[Richard Marsden]

Well I'm back to trying to get pgRouting working again with my planet.osm
file. This has been loaded into Postgres with Osm2po.

I'm not sure if I've got the right parameters, but pretty much every
variation I try results in long running (tens of minutes) before it crashes
with an out of memory error (typically around 39017600).

An example query:

SELECT * FROM shortest_path (
'SELECT id, source, target, cost, reverse_cost FROM osm_topo' , 44070476,
44070478, true, true );

I've also tried a few different functions other than shortest_path(). The
node numbers were picked from a query of the first few rows. I also checked
indexes: osm2po produced indexes on source, target, etc.

It seems that the inner query which is passed as a parameter to
shortest_path (or any of the other functions) might be querying the entire
dataset?  Which of course is huge as I've got the entire OSM planet file
loaded into PostGres. So I tried adding a WHERE clause to the inner SELECT
that only queries x1,y1 coordinates within a range (x1,y1 for Node 44070476
is about 55,51, so I chose 50.0->60.0 and 45.0->56.0 as my ranges).

No better.

So I think I'm really pushing the limits. planet.osm is of course huge, and
despite the significant pruning by osm2po the resulting routing network is
still very large. I guess pgRouting just doesn't scale to such admittedly
large datasets.
(I note that the online OpenLayers-based demos are limited to individual
cities)

I wish to eventually do my bulk routing on a country-by-country basis, but
it would not be practical to load each country individually. I'll look to
see if there are any other approaches, perhaps with a different offline
routing engine (using a web service is not deemed practical), but it looks
like this project is probably going to be dead in the water.


Richard Marsden
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