[mapserver-dev] Implement msPostgisLayerGetExtent

[Stephen Woodbridge]

On 12/31/2013 11:46 AM, Even Rouault wrote:
> Just an idea :
>
> Similarly to ( http://mapserver.org/mapfile/projection.html#projection-auto )
> PROJECTION
> 	AUTO
> END
>
> why not having ?
> EXTENT AUTO
>
> When this is defined, it would go to the possibly expensive computation.
>
> So we would have :
> - no EXTENT specified at layer level
> - EXTENT xmin ymin xmax ymax
> - EXTENT AUTO
>
> The question is when no EXTENT is specified, should that be equivalent to
> "EXTENT AUTO" for layers where it is cheap such as shapefiles ? We would
> probably a virtual method HasFastExtentComputation to do that

Even,

I like this syntax. If the EXTENT is not defined at the LAYER level then 
it should default MAP EXTENT and if that is not defined throw an error. 
This implies that EXTENT AUTO at the map level is inherited at the layer 
if not defined at the layer.

There is additional discussion on this @
https://github.com/mapserver/mapserver/pull/4825

-Steve W