[OSM-dev] segment discussion - fork of mysql partitioning

[Andy Robinson]

I'll reinforce my wish to be able to override a way's characteristics. No
problem for nodes of course but if we loose segments then there is for
instance no possibility for me to continue to tag a canal way segment as
being a lock. At the moment I tag the nodes at each end as "lock_gate" and
theoretically I could do the same with tunnels ("portal") or bridges
("abutment") but then I would need a way to work out that the section
between is a tunnel or bridge classification, especially if there is more
than one of these features on the same way (very possible).

So what I am saying is that I think I still need segments. But that is not
to say that the segment could not become a sub_category of the way and only
used when it needs to be used, otherwise there is no segment between two
points, just the way of ordered nodes.

Linked to the same thing is a practical comment.

When editing map data at the moment I create segments and then turn these
into ways. Where I have the full details of the eventual way I could make
the way directly rather than having to make the segments first, it's been
discussed plenty of times before. However there are many instances when I
don't really want to create the way at all, simply because the information I
have about any eventual way along that pathway is negligible. Perhaps for
instance I traversed along a 100m section of new highway while mapping one
that crossed at a staggered junction. I don't really want to make that 100m
into a way, I'd rather leave it as segments as its easier to see that its
unfinished business.

So, before we consign segments to the OSM trash we need to ensure the tools
and user experience for ways are suitably refined. If that can be achieved
then I have no problem in changing or eliminating segments if that makes
long-term sense for the db structure and platform performance. Including
client software performance.

Cheers

Andy

Andy Robinson
Andy_J_Robinson at blueyonder.co.uk 

>-----Original Message-----
>From: dev-bounces at openstreetmap.org [mailto:dev-bounces at openstreetmap.org]
>On Behalf Of Andreas Brauchli
>Sent: 31 August 2006 7:19 AM
>To: Richard Fairhurst
>Cc: dev at openstreetmap.org
>Subject: Re: [OSM-dev] segment discussion - fork of mysql partitioning
>
>On Wed, 2006-08-30 at 15:30 +0100, Richard Fairhurst wrote:
>> Removing segments and making ways a list of ordered nodes would also
>> reduce the db load here.
>
>i understand this, but segments are useful for sub-informations like
>bridge=yes, tunnel=yes, etc. which do not apply to the whole way - a
>possibility around this would be to make ways groupable (arrays of
>ways), which is technically not very different to having segments
>grouped..
>
>how would you handle these cases without segments? have a seperate way
>with same properties + the extra properties (i.e. like tunnel=yes)
>
>andreas
>
>
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