A deep navigator is a type of dynamic drill-down navigator which applies on-the-fly aggregation of result values across the entire result set for a query.
It is based on values specified in flat fields only. Navigators provide functionality for drilling down into the query results based on value distribution of one or more individual fields.
Deep navigators reflect the entire result set and usually require re-indexing when a new navigator is added. This type of navigator is recommended for all commonly used navigators associated with individual fields (not scope fields).