Ann,

>> I don't see anything particularly strange in your case. Equality tests
>> use indexes, inequality tests don't. Why do you expect is null and is
>> not null to behave differently?

A> Err, _not_ quite. In fact the key is the "_not_". Since the
A> beginning of (its) InterBase / Firebird have _not_ used
A> indexes with _NOT_ conditions.

My wording was unclear. I didnt mean that *only* equality tests use
indexes, just that inequality test don't, AFAICS.

A> Whether (or _not_) that's
A> appropriate with expressions like NOT NULL is debatable.

yep, and that's the point of the suggestion (see the rest of the
thread).
--
Nando Dessena
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