[OSM-dev] osm2pgsql, -e option might affect too many tiles

[marqqs at gmx.eu]

Hi Andy,

thanks for reply!

You're right, the whole way needs to be rerendered if one node is moved and the way is displayed as a dashed line.

Nevertheless, it would be a nice feature if only the node's tile and maybe the neighboring tiles would be rerendered if someone changed just one of the node's tags. Presently, if you change the name of a tram station, several hundreds of tiles will be rendered again.

Sure, it could be worse, rendering just the diffs saves a lot of time, I can live with this rendering overhead. osm2pgsql seems to be really fast too. Thanks to everyone who contributed to osm2pgsql!

Markus

-------- Original-Nachricht --------
> Datum: Thu, 1 Sep 2011 08:31:01 +0100
> Von: Andy Allan <gravitystorm at gmail.com>
> An: marqqs at gmx.eu
> CC: dev at openstreetmap.org
> Betreff: Re: [OSM-dev] osm2pgsql, -e option might affect too many tiles

> I'm not sure that osm2pgsql is massively sophisticated with this
> situation, since it certainly doesn't know anything about the
> stylesheets.
> 
> If, for example, the node was moved slightly, and all those lines were
> dashes, then the full length of every line would need to be redrawn.
> Alternatively, if it was just a tag change but now became e.g. a pub,
> then any blocking symbolizer along those lines (e.g. road names) could
> have moved and again everything needs redrawing.
> 
> That said, I'm sure there's plenty of optimizations that can be made
> in this area.
> 
> Cheers,
> Andy
> 
> On Thu, Sep 1, 2011 at 7:10 AM,  <marqqs at gmx.eu> wrote:
> > Hello,
> >
> > I'm using osm2pgsql with the excellent -e option which allows me to
> generate dirty-tiles lists. It's my observation that the output can be somewhat
> extensive if you just change ONE node. For example:
> >
> > I change the name of a single node. This causes osm2pgsql to put not
> only the node's tile on the list but also every tile which is touched by every
> way which uses this single node. I guess there's a reason for this
> behaviour. Does anybody know situations in which it is really necessary to
> rerender all these ways?
> >
> > Markus
> >
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> >