Hi Maxim, 2010/10/12 Maxim Dubinin <s...@gis-lab.info>
> Hi osmosis-devs, > > On our regional extraction system we've ran into what seems to be a > bug. > > Relations, that are members by themselves are dropped while extracting. > > Example of such relation: > http://www.openstreetmap.org/browse/relation/358215 > > Code and example to reproduce this behavior is attached. > Thanks for the detailed example, it makes it much easier to diagnose your issue. The reason for the dropped relation is a limitation of how Osmosis performs bounding-box/bounding-polygon processing. Osmosis processes all data in a stream. First it processes all nodes one by one and keeps track of which nodes are in the bounding box. It then processes each way one by one and uses the node list to determine which ways are in the bounding box. Then it processes the relations one by one and uses the list of nodes, ways, and already selected relations to determine if a relation is in the bounding box. In your example, relation 795 is processed first and contains relation 792. But 792 hasn't been processed (in your example, the two ids are out of order) yet so Osmosis doesn't know that it will be inside the bounding box and ignores it. It then processes 792 which has two ways inside the bounding box so it includes that relation. But it never goes back to include relation 795 because it has forgotten about it. In your example, if you switched the order of relation 792 and 795 then 795 *would* get included. The only way to avoid this limitation is to replace your existing --bp step: --bp file=test.poly with --bp file=test.poly completeWays=yes completeRelations=yes This makes Osmosis run *much* slower and might not be acceptable. With those options enabled, it builds temporary stores of nodes, ways and relations so that it can go back and randomly access data. But the temporary data stores are quite slow which has a very large impact on performance. Hope that helps. Brett
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