[OSM-dev] Ways with 40k nodes, was: osmosis pgsql schema

Andy Allan gravitystorm at gmail.com
Fri Oct 31 12:42:37 GMT 2008


On Fri, Oct 31, 2008 at 11:51 AM, Stefan de Konink <stefan at konink.de> wrote:

> Imagine a way as a relation.

OK. This relation is the Eurasian coastline. 17M nodes, lets say.

> Where every difference in way is
> represented as a subtree under it.

Let's say it's all natural coastline, and was created at the same
time. So I have one 'subtree'.

> In that case common tags are equal
> and managed at top level.

Yep, that's a good idea.

> In case of a partial checkout you would only
> fetch the subtrees (relations) that are in your bbox and their parent.

The one subtree has 17M nodes, and I get the parent relation with the
coastline tags too.

No, hang on, that would be daft. I'd be better off making subtrees
limited to about 1000 nodes or thereabouts, to improve the efficiency
of partial checkouts. So then I would have sensibly sized subtrees
(lets call them 'ways') and the master super-tree (lets call it a
relation).

Oh.

Cheers,
Andy




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