[OSM-dev] multiple tables

[Artem Pavlenko]

Jon,

On Tuesday 27 February 2007 22:18, Jon Burgess wrote:
> On Tue, 2007-02-27 at 21:12 +0000, Artem Pavlenko wrote:
> > Here is 'multiple tables' patch for osm2pgsql which creates three tables
> > - one per geometry type. I think it makes creating styles/rules/filters a
> > little bit more manageable.
> >
> > How about filtering out  'coastlines'?
> >
> > Cheers,
> > Artem
>
> Do you happen to have a corresponding patch to osm.xml which uses these
> new table names?

I'm using my own osm.xml... I can see osm.xml changing quite a bit after 
carto-meetup. Lets hold back on this patch till Sunday.   
>
> Does dropping the coastline data make any significant performance
> difference? 
Not really. It just makes cleaner SQL.
> I'd suspect we shouldn't drop it from osm2pgsql until we 
> have a replacement set of shapefiles which a reasonable polygon
> coastline coverage.

I was alway thinking about incremental upgrade from coastines to 
coastpolygons. I have dataset with the _whole pgs coastline_ data (much 
better coverage than osm coastline) plus polygons for the England and Wales + 
Dublin.
 
>
> Personally i'd like to start with an interim approach of converting the
> coastline rendering to a line style like I mentioned previously. IMO a
> thin blue line is an improvement over the present grey triangles (at
> least until the coastline polygons get completed).

Exactly, with my approach we can render blue line where there's no Polygons 
and filled areas otherwise. 

>
> I've also been wondering whether creating specific tables for each of
> the SQL select queries in osm.xml might speed things up a little. 
Yes, it should.
> Since 
> the same query gets run multiple times it seems logical to me that
> performing this once and storing in a separate table would be a win.
I think just splitting data based on geometry type might be good enough. Lets 
see. I'd like to try rendering all 'line' features (roads/rail/etc) 
using 'layer' tag and see if this is producing good cartography. 

> I  think the previous consensus was that osm2pgsql+osm.xml are a fairly
> tightly coupled pair which need to be kept in sync anyway.

Yes, seems this way. 

Cheers,
Artem

>
> 	Jon
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