[OSM-dev] Lite OSM backend

Raphael Jacquot sxpert at esitcom.org
Fri Sep 8 10:02:54 BST 2006


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Nicola Ranaldo wrote:

> Yes, i did some experimentation with r-tree index and postgres as it has a 
> very nice set of geometric operators. The main problem is not in seeking the 
> index but in retrieving data as they ar not ordered in the db pages. It's 
> sufficient a big map query to invalidate the cache of the entire db resulting 
> in a huge disk access for subsequent query. So, as you suggest in your 
> excellent analisys, the backend has to be "clustered" on spatial information. 
> I do not know if actual free SQL implementation permits this (for a server 
> side reengineering), howewer this could be emulated using a very simple 
> database schema with two columns, the first with spatial information 
> (indexed), and the second with a a variable field storing all the geometric 
> objects and their tags with a compact encoding. On clients and embedded 
> devices not using a full featured sql server the sorted binary file is a very 
> good idea.

you've missed some things in the document, such as:

http://www.postgresql.org/docs/current/interactive/ddl-partitioning.html
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