[OSM-talk] Relations not always brilliant

[Steve Hill]

On Mon, 7 Apr 2008, Frederik Ramm wrote:

> I assume it will usually be easier to check a machine-readable relation than 
> to compare tags.

Possibly.  There may be cause for having machine generated relations which 
are kept up to date by the server when data is committed so the people 
editing the data don't need to care about them (such relations would need 
to be read-only and tagged in a way to make it clear they aren't normal 
editable relations).  I think that'd be easier for people submitting the 
data than having to deal with these relations directly (which as you say, 
are only there for efficency reasons)

In the end, moving *all* tags into relations might be the best thing to 
do, but I think the editors need a lot of work before that is a viable 
option.  At the moment we have a rather confusing mix.

> it seems unnecessary to ask them to also group by tags which 
> involves finding out which tags to group by, which bounding box so search in, 
> splitting tag values at semicolons etc.

Unless you can ensure that the relations exist on *all* appropriate 
objects, they will have to group by tags anyway.  (And I don't believe you 
can ensure this without some automatic daemon fixing up the relations on 
all the data as it is submitted).

> Rather than have one million systems implement their own ways of guessing 
> what was meant, I'd like to put this explicitly in the database (or at least 
> have *one* central system do the grouping consinstently).

This sounds sensible.  But as mentioned, I think for it to be achieveable 
we either need a lot of improvement on the editors to make relations more 
obvious and intuitive, or we need some automatic stuff to generate the 
relations that can be unambiguously derived from other data.  (Or both)

I'm concerned that the data structure might be outpacing the editors too 
much and this could be raising the bar to entry for mappers.

> But this discussion is becoming much too theoretical.

Well yeah, but sometimes it's good to bash theoretical ideas around to see 
what works. :)

  - Steve
    xmpp:steve at nexusuk.org   sip:steve at nexusuk.org   http://www.nexusuk.org/

      Servatis a periculum, servatis a maleficum - Whisper, Evanescence