Routing engine problems: partition_id AND frequent exceptions in responses

Question

Hi.
I want to use Oracle routing engine with Oracle Spatial 10gR2 for Europe.
I have tables NODE, EDGE, SIGN_POST and PARTITION populated okay with data from a data vendor.
I have 600000 edges and 415000 nodes. 128 partitions were generated by
using: exec SDO_ROUTER_PARTITION.partition_router('NODE_PART', 4000);
Two issues occur to me:
1. select num_nodes from partition where partition_id = 0; returns 390 nodes, but neither in table node nor edge are records with partition_id = 0, which is as I have learned the Highway Partition. Does that make sense?
2. Route requests sometimes return correct results, but more frequently routing engine exceptions:
Most popular are:
- Route not found between destination/source node and highway network!
- mbrAwareAStarSearch could not find a route!
What might be wrong?
I also experience both problems with the NAVTEQ example data for San Francisco extracted from sf_routing.zip.
Below find requests leading to exceptions indicated using NAVTEQ example data extracted from sf_routing.zip in order to make the described reproducable:
1. Route not found between destination/source node and highway network!:
<?xml version="1.0" standalone="yes"?>
<route_request id="8"
route_preference="shortest"
road_preference="highway"
return_driving_directions="false"
distance_unit="km"
time_unit="hour"
     return_route_geometry="true"
pre_geocoded_locations="true">
<start_location>
<pre_geocoded_location id="1">
<edge_id>-37847628</edge_id>
<percent>.5</percent>
<side>L</side>
</pre_geocoded_location>
</start_location>
<end_location>
<pre_geocoded_location id="2">
<edge_id>-37846969</edge_id>
<percent>.5</percent>
<side>R</side>
</pre_geocoded_location>
</end_location>
</route_request>
2. - mbrAwareAStarSearch could not find a route!
<?xml version="1.0" standalone="yes"?>
<route_request id="8"
route_preference="shortest"
road_preference="highway"
return_driving_directions="false"
distance_unit="km"
time_unit="hour"
     return_route_geometry="true"
pre_geocoded_locations="true">
<start_location>
<pre_geocoded_location id="1">
<edge_id>-37827163</edge_id>
<percent>.5</percent>
<side>R</side>
</pre_geocoded_location>
</start_location>
<end_location>
<pre_geocoded_location id="2">
<edge_id>-37847628</edge_id>
<percent>.5</percent>
<side>R</side>
</pre_geocoded_location>
</end_location>
</route_request>

Answer 1

The highway partition, partition zero, is "logical" idea. That is it only exists in the partition table. Each node and edge in the data belongs to a partition that it shares with other nodes or edges in the same physical area. This physical relationship is shown in the partition ids stored in the edge and node tables. Once these partitions are figured out each edge is looked at to see if it's a highway edge, that is, it has a func_class of 1 or 2. Once this is done these edges have their start and end nodes classified as highway nodes and those are considered to be in partition zero also.
I've run into the MBR error you're seeing in my testing and have been looking into it. Forgive my poor analogy, but there appear to be "holes" in the highway system. If one has a major artery, say interstate 95 coming out of FL, all routes between FL and VA are going to want to use that major artery. If there was a "hole" in interstate 95, a section that was not classified as a highway section thus not in partition 0, those routes would be dropped as unusable. If all the routes get dropped in this way you get the mbrAwareAStarSearch error.
I haven't seen the other error but I'll use your example and have a look into it.