Segment Assignment Policy
Unlike the legacy policy, described in Legacy Assignment Policy that ensures that documents are evenly distributed across forests in the database, the segment policy ensures that fragments are evenly distributed across the forests. The segment policy assigns fragments to forests based on their document URIs to allow for fast locking.
The segment policy is the most efficient rebalancing policy when you are adding or reducing the number of forests by 30% or more. For example, if the number of forests doubles, the half of the fragments in the existing forests are assigned to the newly added forests. Conversely, if the number of forests is reduced by half, all of the fragments in a retired forests are assigned to the remaining forests.