What is more efficient?

[Dan Wiggin]

If I work with groups, whats the best option do do? Use a multiple lucene
index for every group or is bettter an unique index.
For example:
I'm working with groups of people, and the action to add or delete is in
group level but the search is on all groups.
What do you think is the best implementation in lucene? I have any number of
index limitation in Multisearcher?