This one's fairly wild, I'm interested to see what the gurus think...
You could create a bitset and mark each document retrieved by the appropriate bit position (using the Lucene document id). Persist this bitset (assuming you need it across sessions). Be careful, I wouldn't persist it via the toString(), persist it as a binary entity. It depends on how many docs we're talking about I guess.... Anyway, let's say you have accumulated one of these. Create a filter with the XOR of the persisted bitset, and pass that filter on to subsequent searches...... When the search comes back, set the bits in your (persisted) bitset and save it away. Repeat as needed.... I have no idea if this would help in your particular situation... And, any time your index changed, any persisted bitsets would be invalid. Anyway, it may even work. See the Filters in Lucene for what filters are all about. Erick
