[Gdal-dev] filtering on an OGRVRTDataSource

[Frank Warmerdam]

On 1/27/06, Charlton Purvis <cplist at earthlink.net> wrote:
> Hi, folks:
>
> Can I do any type of filtering on a OGRVRTDataSource?  Specifically, I'm
> looking to stick something into a MapServer FILTER string that would look
> something like:
>
> FILTER "WHERE lon % 5 = 0 and lat % 5 = 0"
>
> Where the '%' is mod.  Basically, give me every 5DD value.
>
> I just pinged the MS folks to see if I could add the % functionality to the
> EXPRESSION string, but it would be nicer to get OGR to do it before shipping
> the result set to MS.

Charlton,

I can see that such capability would be desirable, but it
doesn't existing in OGR at this time, except for cases where
the underlying database supports it.

What would need to be done is to add the evaluation of
mathematical operators to the OGR SQL expression parser
and evaluator.   This would be a substantial effort, and I'm not
planning to do it in the near future.

Best regards,
--
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