[Gdal-dev] PG-Driver supporting no views?

[Carl Anderson]

Frank Warmerdam wrote:
> Tyler Mitchell wrote:
> 
>> Is this just because there isn't an entry in geometry_columns?
>>
>> Tyler
> 
> 
> Tyler,
> 
> The OGR PG driver isn't restricted to stuff that appears in 
> GEOMETRY_COLUMNS.
> I use the following magical query to get a list of tables that can be 
> treated
> as layers:
> 
>                          "DECLARE mycursor CURSOR for "
>                          "SELECT relname FROM pg_class "
>                          "WHERE relkind = 'r' AND relname !~ '^pg'" );
> 

                  "DECLARE mycursor CURSOR for "
                  "SELECT relname FROM pg_class "
                  "WHERE (relkind in ('r','v') AND relname !~ '^pg'" );

> I think I copied that from somewhere else originally.  The GEOMETRY_COLUMNS
> is currently only used to lookup SRID values.
> 
> So I think the problem is that my query only idenfies proper tables, not 
> views.
> If anyone can suggest an appropriate change to pick up queries too, I 
> can update
> it more easily.
> 
> Best regards,

Frank,

The current method scans and describes every table in the database. 
This can take a very long time to do.  I have 2000+ tables and the 
initialization of the OGR Pg driver takes almost a minute.  From a 
practical standing that precludes my using in user interfaces.

IMHO for large installations a "dictionary" of geometry tables will be 
necessary.  To see what is approved for use.  GEOMETRY_COLUMNS seems to 
have been designed with that in mind.

the OGR_PG driver also supports tables that lack geometry columns and 
using GEOMETRY_COLUMNS for that may be a stretch but leaving the 
f_geometry_column field as an empty string could be (mis)used to provide 
that support.

C.


-- 
Carl Anderson
GIS Manager, Fulton County E&CD
404.730.8026
carl.anderson at co.fulton.ga.us