[OSM-talk] Xapi and version attribute

[80n]

On Wed, May 6, 2009 at 10:47 PM, Rob Reid <rob at robreid.co.nz> wrote:

> Maarten Deen wrote the following on 07/05/2009 07:31:
> > Is it possible that in the Xapi servers, the version attribute is only
> present
> > in nodes that have been changed after the 0.6 transition?
> > If I download data from Xapi, it is missing in most nodes, except for
> those
> > edited after 2009-04-28 (in my dataset).
> >
> See 80n's email to talk about it a couple of days ago
> http://lists.openstreetmap.org/pipermail/talk/2009-May/036563.html
> > I think this is quite an important issue as the 0.6 api will not accept
> uploads
> > without a version.
> >
> I'm not sure Xapi is your best source of data if you are planning on
> editing it and feeding  it back into the main api as there is no
> guarantee you are dealing with the latest data.
> For example around the 5th May it was returning data from the 29th April
> and I could see it slowly catching up with each query I did over the
> next few days.
>

It has been playing catchup since the 0.6 upgrade and is currently not far
behind.  It's normal state is to be about 5 minutes behind the live
database.


> All the editing programs (except  maybe potlatch which has its own
> interface) go through the main api for this reason, I think Xapi is
> intended more for search and querying the data in a read-only way where
> having the guaranteed latest version is not so important.
> Now that the api supports versions you may be safe since any edits you
> try where you don't have the current version will be rejected but if you
> were doing it pre-api 0.6 its possible you were reverting other peoples
> changes.
>

Unlikely since the lag is normally only 5 minutes and most areas don't
change very much at all.  In practice the risk of edit collisions (unless
there's a mapping party or something intense happening) is very very low.
0.6 gives you version protection now anyway, so it's perfectly safe (famous
last words).

80n





>
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>
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