>>That's just how engine works. I don't think there is anything wrong here as long as it is documented.
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>I know that and I know it is not a bug. I just think it would be VERY nice if the engine could figure it out and optimize it. Or I guess in the help file topic for BETWEEN and EMPTY there could be a note something like "You shouldn't actually use these functions because they stink!"
>

You can not use EMPTY() (and AFAIK it's documented in Help) and you should use between with the field, not with a variable between two field values. That's all.