[josm-dev] Problem with large changeset

[Sebastian Klein]

Alan Mintz wrote:
> At 2010-07-06 01:16, Sebastian Klein wrote:
>>  (But you said something about way conflicts, have you analysed these 
>> as well?)
> 
> Not quite yet. The few I looked at were because the ways contained new 
> nodes (with negative IDs) that had not been updated with the 
> newly-assigned positive IDs. I'm hoping they are all this way.

Ok, this is expected...

>> All this is only true if you upload in a single request. In chunked 
>> mode, this applies for each chunk separately.
>>  If you have a problem in a later chunk, it is usually a good idea to 
>> save the file anyway because JOSM has already processed the server 
>> responses from the successful chunks and remembers what has been 
>> uploaded so far.
> 
> I hadn't noticed that ability. The last time I looked, my only choice 
> was individual or all, and individual took way too long. I'll definitely 
> to do this for large changesets in the future. Perhaps JOSM should 
> suggest this by default when you try to upload more than x objects.

It is not recommended for newby users: For referential integrity,  JOSM 
first uploads all nodes, then all ways and finally all relations. If you 
encounter conflict in the second chunk and completely abort the editing 
session for some reason, then you leave quite a mess behind (useless 
cloud of nodes).

Now that I think about it, the upload order should be optimized:
  * first "singleton" nodes (POIs)
  * then for each way: all way nodes and then the way itself
  * then relations

Another workaround if you expect conflicts:

Filter for "modified" (inverted), then select small parts and do "upload 
selection". (Deleting objects might require a final "normal" upload.)


Sebastian