• A FullCompactPolicy that compacts all slots into one whenever the "tail" of slots with smaller arities exceeds together a certain arity. The idea is that the arity-based policy guarantees occasional full-compaction, but the time interval between full-compaction increases exponentially. This add-on policy caps the increase at a certain arity, and schedules full-compacts at regular intervals afterwards. This policy is appropriate when auto-compacts are managed per generation-arity. In this case, a full optimization can occasionally be triggered to purge the deletes. If not, the deletes occurring in later slots would never be deleted, incurring performance costs at query-time and extra disk space consumption.
Whenever the long tail total arity reaches maxArity, a full compact is scheduled. The "long tail" are the slots whose span has an arity inferior to this parameter. This is generally a multiple of the auto-compact Arity policy arity parameter.