>>>Rushmore optimizes an INDEX ... FOR lExpression command if lExpression is an optimizable expression. For best performance, use an optimizable expression in the FOR clause.
>>
>>Jess, this means that the expression in the FOR clause has to itself be optimizable. That means there must be another index on that expression.
>
>So it clearly explains that an INDEX...FOR (Filtered Index) can be optimizable if the expression is optimizable.

But this a meaningless point. The FIltered index will NOT be used in any optimization, only the index that made the filtered clause optimizable. IOW, for the example you gave above....

INDEX ON code TAG code FOR code = 'I'

is only optimizable if you also have an index

INDEX ON Code TAG Whatever

So, this really means that the first index is not usable at all. Any expression will not use the first (filtered) index, but the second, non-filtered one.


>CALCU SUM blah..blah.. && not optimizable anymore
>SCAN FOR.... && not optimizable anymore