Andreas Kalsch wrote:
> I have set up a OSM database with Germany data. Now I want to update my 
> data daily. I have not found diff files for Germany so I want to use the 
> global diff files, which are not too big.
> To re-import German data every day would be too expensive - it already 
> took some hours.
>
> In Osmosis, I tried this:
>
> osmosis/bin/osmosis --read-xml-change data/osm/20080916-20080917.osc 
> --bounding-polygon data/germany2pts.txt --apply-change --write-mysql 
> host=localhost database=osm_de user=user password=xxx
>
> Result:
>
> Sep 17, 2008 10:05:15 PM com.bretth.osmosis.core.Osmosis main
> INFO: Osmosis Version 0.29
> Sep 17, 2008 10:05:15 PM com.bretth.osmosis.core.Osmosis main
> INFO: Preparing pipeline.
> Sep 17, 2008 10:05:16 PM com.bretth.osmosis.core.Osmosis main
> SEVERE: Execution aborted.
> com.bretth.osmosis.core.OsmosisRuntimeException: Task 2-bounding-polygon 
> does not support data provided by default pipe stored at level 1 in the 
> default pipe stack.
>     at 
> com.bretth.osmosis.core.pipeline.common.PipeTasks.retrieveTask(PipeTasks.java:154)
>     at 
> com.bretth.osmosis.core.pipeline.common.TaskManager.getInputTask(TaskManager.java:164)
>     at 
> com.bretth.osmosis.core.pipeline.v0_5.SinkSourceManager.connect(SinkSourceManager.java:51)
>     at 
> com.bretth.osmosis.core.pipeline.common.Pipeline.connectTasks(Pipeline.java:69)
>     at 
> com.bretth.osmosis.core.pipeline.common.Pipeline.prepare(Pipeline.java:111)
>     at com.bretth.osmosis.core.Osmosis.main(Osmosis.java:49)
>
> So am I right thinking, that the bounding polygon filter does not 
> support the input of change data?
>   
That's correct.  There is no way of writing a bounding box task for 
managing changeset data.  Take this scenario for example.
A way already exists in your database related to several nodes.
Somebody modifies the way but doesn't touch the nodes.
The next changeset will contain the updated way within a <modify> 
element but not the nodes.
A bounding box task will have no way of knowing whether the way is 
inside or outside the bounding box.

All is not lost however.
The simple answer is just to import the diff for the entire world.  It's 
approximately 10MB of compressed data per day so the database will only 
grow steadily.
The slightly more complicated answer is to import the entire world diffs 
but then run an additional query to delete data not inside the bounding 
box.  This would only have to be run occasionally.

A more complicated solution (involving some coding) could be as follows:
Before applying a changeset, re-order the changeset to preserve 
referential integrity.  Osmosis can do this already with the --sort task.
Only write nodes that are inside the bounding box and check to see if 
each node already exists in the database.
For every way write, check the nodes that should by this point already 
exist in the database to see if the way is inside the bounding box.
For every relation write, check to see if any members already exist in 
the database.

I don't have any immediate plans to attempt the correct solution above 
due to lack of time, but it would be neat if somebody could get it working.

Brett


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