The whole point is that you have more RAM than data, not less. If you are trying to do queries in LDAP and all of the data (entry db and index dbs) do not fit i

The whole point is that you have more RAM than data, not less. If you are trying to do queries in LDAP and all of the data (entry db and index dbs) do not fit in RAM, then forget about it. This is why you would design the system to take growth into account. Modern LDAP servers -- in conjunction with LDAP proxy servers -- are designed to do this very thing. Verison has their 75 million wireless subscriber "database" in LDAP, not a RDBMS, and the entire dataset is in memory (spread across dozens of servers).