[OSM-dev] Way as Relation
Stefan de Konink
skinkie at xs4all.nl
Thu May 29 20:16:45 BST 2008
Jon Burgess schreef:
> On Thu, 2008-05-29 at 16:51 +0200, Stefan de Konink wrote:
>> Maybe this is discussed before, but I want to know what the general
>> opinion is about it.
>> I wonder if we can skip a table of ways, and instead make it a relation.
>> And it would look as:
>> <relation id="77" visible="true" timestamp="2006-03-14T10:07:23+00:00" user="fred">
>> <member type="relation" ref="343" role="from" />
>> <member type="node" ref="911" role="at" />
>> <member type="relation" ref="227" role="to" />
>> <tag k="type" v="way"/>
>> Is there a reason not to implement it this way?
> I'm not sure I understand, but I think you are proposing that ways be
> implemented as a type of relation. Two problems with this:-
> 1) The list of nodes in a way is ordered. The members of a relation are
> not ordered.
I have implemented an index for relations too.
> 2) The relation IDs overlap with the way IDs. You would probably need to
> renumber either all the ways or relations.
True, but if that is the biggest problem...
> In general though, do you really want to "optimise" the data by
> converting the 20M concisely defined ways by making them look more like
> the 11k generic relations in the DB. This surely going to expand the
> storage and processing overhead for the ways. That sounds wrong to me.
I'll benchmark both solutions.
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