[Tagging] is tourism a good category for everything cultural?

Ross Scanlon info at 4x4falcon.com
Tue Aug 24 09:29:13 BST 2010

On Tue, 24 Aug 2010 10:03:42 +0200
Ulf Lamping <ulf.lamping at googlemail.com> wrote:

> Am 24.08.2010 09:36, schrieb Ross Scanlon:
> >> Well, I will take a change to 'troll' again about it. This discussion
> >> comes up again and again because we don't have:
> >> a) clear tagging guidelines (*not* rules)
> >> b) mechanism to replace tags
> >
> > Agree totally.
> >
> > This (b) would be easily recitified by normalising the database in regards to tags.
> So how do you easily: "normalise the mappers minds, renderers, editing 
> software in regards to tags"?!?
> Over several years past now, I have seen this discussions come and go. 
> When someone was actually doing something, it usually ended up in a mess 
> of wiki, mappers, editors and renderers disagreeing how to tag 
> something. A confusion causing a *lot* more harm than any good.
> It's simply a misconception, that just "cleaning up" the tag names will 
> lead to an easier mapping experience.
> Regards, ULFL

You have no idea about normalising a database do you.

It has nothing to do with what you have above.

Rather than storing a tag as a key=value, you store it as a unique identifier.

The identifier is then referenced in another table in the database which will provide the key and value.

Lets take an example.

Currently in osm we have a road tagged with the following:

name="A street"

If the database was normalised then the following would occur.

name="A street"

The tagging table would have in it:

for a tag_id of 1000000


for a tag_id of 1000001


Now say that we decide that we no longer wish to call residential ways "residential" but a new name of "house streets".

To change the current database it would take a lot of effort but with a normalised database all we have to do is change the "value=residential" in the tagging database to "value=house_streets" and every way that was tagged residential is now tagged "house streets".

Tags like name would not have a tag_id as they are not unique.

The renderers would simply have to look in the tagging table to see what needs to be displayed.


More information about the Tagging mailing list