[OSM-dev] [OSM-legal-talk] Fwd: license change effect on un-tagged nodes

[Anthony]

On Thu, Jul 7, 2011 at 9:19 AM, Dave F. <davefox at madasafish.com> wrote:
> On 07/07/2011 07:41, Anthony wrote:
>>
>> Thanks Toby.  I'm forwarding this to Dave Fox, who is the one who
>> actually asked the question.
>
>> It follows pretty naturally out of the database schema. Anything that
>> modifies the ways, way_tags or way_nodes tables creates a new version
>> of the way. Things that only affect the node tables such as moving the
>> location of a node or changing tags on the node do not affect any of
>> the way tables so no new version is created.
>>
>> The same thing happens with relations and their members. You can add a
>> maxspeed= tag to a way and it doesn't affect the relation that way is
>> a part of. That would actually make touching long route relations a
>> conflict nightmare so I'm pretty glad this isn't the case.
>
> Thanks to Anthony for asking & Toby for responding.
>
> However that just explains what happens but not why.
>
> I suggest that, to most users, if a node within a way is moved then that way
> is considered to have been modified & should be recorded as such.

Well, I'm pretty sure I agree with you.  Especially if it means we
have to go to 64-bit node ids (which means the node id will be as
large as the node data!).

For the "why", google "database overnormalization".  If that doesn't
make sense, I'm not sure I can explain it.