>Thanks Hilmar,
>The largest table contains about 10 million records and consumes 1.4GB disk space. How many resources it will possibly required? Is there anyway to estimate the possibility that Rushmore would be disabled, so I can warn users about that.

If I understand Rushmore correctly, the calculation will be as follows:

Example: Condition1 AND Condition2 AND Condition3

Supposing that all three parts are Rushmore-optimizable,

Each condition will require 10 million bits = 1.25 million bytes.

Three conditions + 1 result set = 4 sets. Or perhaps the second result set is combined with the third condition - that would require only 3 sets.

4 * 1.25 MB = 5 MB (or 3 * 1.25 MB = 3.75 MB). That shouldn't be a problem on most machines. How many MB RAM do your users have? I assume they are very low, perhaps 16 MB or less (Windows itself, and the program, may consume a lot). I would simply recommend they add more RAM - this should help.

Note that a partially-optimizable query could consume less RAM.

In the calculation, I only included the number of records.

However, the large size of your table is a reason to worry, too: VFP is limited to 2 GB per file.

HTH, Hilmar.