Well, I *suppose* you could get the bitset from the pre-existing filter, copy it to the bitset for your new filter, and play with the bits at the end. I'm not sure how you get rid of your original filter if you use CachingWrapperFilter though.........
But.... As "the guys" have pointed out in other contexts, be really sure your doc IDs don't change out from under you. You can only count on this if you never, Never, NEVER delete anything from the index and then add something else between the times you build the first filter and the time you modify it (at least I think I have this right). That said, I wouldn't go down this route unless you have an actual, real-live performance issue to deal with. Premature optimization being the root of many, many, many evils. It'd be evil to debug if you mess up your filter copying/modification..... Best Erick
