[OSM-talk] Fwd: [Talk-us] [Warning: Potential Flamewar] Clarifying InterstateRelations

Apollinaris Schoell aschoell at gmail.com
Tue Feb 9 03:47:45 GMT 2010

On 8 Feb 2010, at 18:28 , John Smith wrote:

> On 9 February 2010 12:20, Apollinaris Schoell <aschoell at gmail.com> wrote:
>> what is wrong with 2 relations?
>> I didn't say 2 are needed but why do you think 2 is bad?
> It creates redundant data, and makes it easier to get conflicting data
> if both aren't updated consistently.
> It also gives people the opportunity to merge them, possibly incorrectly.

1) theory: tags on the super relation will always supersede tags lower in hierarchy. conflicting tags don't matter. 

2) practical editing: we are talking about a relation hierarch consisting of thousands of members. they have to be split for many reasons. editing speed, upload speed, query speed …
some have been created when Potlatch worked in live mode only and josm speed exponentially decrease with the size of a relation, uploads didn't finish because of network/server interrupts
as an example relation 94043 has 1512 members and 937 versions. this only one direction. other direction has 1525 members. It is not possible to get the history from the server "Sorry, the data for the relation with the id 94043, took too long to retrieve."
any split of any road segment for a bridge, speed limit change … requires a new version and increases the number of members. 
do you still think a potential inconsistency has any relevance compared to this?

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