[OSM-dev] ER Diagram of OSM Database

Paul Norman penorman at mac.com
Tue Dec 13 01:48:20 GMT 2011

> From: Andreas Hubel [mailto:andi at saerdnaer.de]
> Subject: Re: [OSM-dev] ER Diagram of OSM Database
> Hello Parveen,
> Am 12.12.2011 um 19:50 schrieb Parveen Arora:
> > I was searching for ER Diagram of OpenStreetMap's Database to
> > understand completely,
> I think the best way is to understand the different parts step by step
> and not to try to understand everything at the first time.
> > I found one component diagram
> > http://wiki.openstreetmap.org/wiki/Component_overview
> >
> > But I want one only of database?
> There is not one database. The main services provided by the foundation
> actually use two different databases, as shown in the component overview
> you already found.
> Green: PostgreSQL backend
> 	aliases: api db, main db, core db
> Yellow: PostGIS
> 	aliases: osm2pgsql db, Mapnik db

Not all of the green components use the same Postgresql backend. The api
does, but xapi uses GT.M and jxapi uses pgsnapshot.

> We should definitely discuss about using uniform names in future.

I've been using pgsnapshot, pgsimple, pgsql and apidb to describe the four
common ones.

I know the documentation on the types of databases and schemas commonly used
has been worked on by the EWG, and it is better than before, but it can
still easily be confusing. 

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