[OSM-talk] Réf.: Re: All you've ever wanted to know about the french cadastre

[Shaun McDonald]

On 28 Sep 2012, at 06:25, THEVENON Julien <julien_thevenon at yahoo.fr> wrote:

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> Le jeu. 27 sept. 2012 20:18 HAEC, Sarah Hoffmann a écrit :
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>>> This is the real problem for us.
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>> For the sake of completeness: planetwide there are currently
>> 152 million objects. Which means 1/6th of the planet consists of
>> French buildings. Now, there is a real problem.
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> Hi Sara,
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> concerning problem of disk usage by french cadastre data do you have some information?particulary do you know how is it stored in database?
> to be allowed to use cadastre data we have to add a source key which is long about 40 characters to each way drawn thanks cadastre data due to legal agreement with french office goverment providing cadastre data.
> do you know is this key is duplicatd for each building in the database or if there is a smart storage? if not it would be interesting to know which part of the size is for the key itself and which part is for the geometry. I think that for buildings composed of one way and 4 nodes the space required by the could be greater than for geometry.
> if this is the case there is perhaps a way to factorise the source key and dramatically reduce disk usage.

The way to reduce the disk space for stuff imported in the future is to store that source once on the changeset instead.

Shaun