Interesting.

Could you add some kind of scoping? Something like ${feature.bounds} for the 
bounds of the current feature?

Jody

On 25/05/2010, at 7:57 PM, Andrea Aime wrote:

> Hi,
> I'm looking for a way to make EnvFunction used in filters
> play nice with databases and stores in general.
> 
> What happens now is that the function is not recognized and
> thus forces that part of the filter to be evaluated in memory.
> 
> It would be nice to perform the param value expansion into
> a literal so that the store can use it for optimized filtering.
> A good place to perform the substitution is the 
> SimplifyingFilterVisitor, which is already in use in a number
> of places.
> 
> What we need to be sure about, though, is that the param
> value is not going to change on a feature by feature basis,
> which is not something we might not be able to take for granted...
> 
> How do we deal with this? Add a "static" flag to the function
> where the use can declare if the function values are going to
> change during a data access?
> 
> Or maybe add some global flag, some system variable, to declare
> the same?
> 
> Imho the case of param values not changing feature by feature is
> the most common and having an optimization for it would be good,
> yet the dynamic case could be of interest as well
> 
> Opinions?
> 
> Cheers
> Andrea
> 
> -- 
> Andrea Aime
> OpenGeo - http://opengeo.org
> Expert service straight from the developers.
> 
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> 
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