FWIW the simplifier in my CSS converter just adds (or removes) the IS NOT
NULL logic. I've tried it a few ways and this seems the only way to be
consistent across two-state and three-state logic systems.
Might be nice if GeoTools were to emulate three-state logic for in-memory
systems, but I'm not sure it's feasible to have three-state for all
backends.
On Mon, Feb 3, 2014 at 3:45 PM, Andrea Aime <andrea.a...@geo-solutions.it>wrote:
> On Mon, Feb 3, 2014 at 9:41 PM, Jody Garnett <jody.garn...@gmail.com>wrote:
>
>> I admit de morgan is a pain to implement, but I would find the result
>> more intuitive then null checks suddenly appearing.
>>
>
> Easier to read, yes, easier to index, maybe, but ... more intuitive?
> How do you explain a end user that he wrote "not(a > 3 and b = 5 and c <=
> 10)"
> and the code is running "a <=3 or b < 5 or b > 5 or c > 10" and that is
> fully equivalent,
> actually, it is better?
>
> Also, I still have to verify that what we discussed so far actually brings
> the database
> 3 state logic back to our 2 state one in a fully equivalent manner: think
> nested filters
> or combinations, I believe that once even one bit is unknown, everything
> just flips
> into that state, and that the only way to get out of it is to have
> explicit "is null", "is not null"
> statements...
> Have to check.
>
> Cheers
> Andrea
>
>
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