[OSM-dev] Mapnik doesn't find geometry columns

[Frederik Ramm]

Hi,

Hans Musil wrote:
> Sure, exactly this was the problem! That's why I wanted to know how to 
> tell Mapnik what the geometry column is. It didn't find it by itself and 
> just left it blank in the SQL query.

I had similar problems in the past, intermittently. They do not stem 
from Mapnik not finding the geometry columns - it does an initialisation 
query on startup which you can find in the PostGIS log files if you look 
closely. However, there seem to be situations where Mapnik (or someone 
else) drops the PostGIS connection halfway through, and then Mapnik is 
clever enough to allocate a new connection from its pool but for some 
reason the initialising query is not always made for all connections and 
you end up having some stale ones in the pool that lack the geo column 
info. At least that was my diagnosis at the time... I think my 
application had somehow messed up proper PostGIS connectivity or so. 
Look for

             geometryColumn_=rs->getValue("f_geometry_column");

in the Postgis input plugin and put some debug print statements there to 
find out what is going on.

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"