What I don't like is the strong focus on one (LMDB) database backend, despite of all the stupid things Oracle does.There are big issues with the two BerkeleyDB backends for many installations so it had to be abandoned. I'll let Howard or Quanah take this part of the discussion further should they choose to. Unfortunately, no other backend is in shape to be useable as a main database in production.
BerkeleyDB 6 and later are not license compatible with OpenLDAP. Thus one of the "stupid" things Oracle did is ensure the removal of the back-bdb and back-hdb backends from OpenLDAP as well as BerkeleyDB from numerous other pieces of software. It has already been noted that back-bdb/hdb are deprecated and that the supported primary database backend going forward from that point was back-mdb.
More to the point, as this email is discussing OpenLDAP 2.5, there will be no back-bdb/hdb after OpenLDAP 2.4. They've already been removed from openldap-master. One thing there that would be helpful is ensuring that all references to them have been removed from the documentation in master.
Regards, Quanah -- Quanah Gibson-Mount Product Architect Symas Corporation Packaged, certified, and supported LDAP solutions powered by OpenLDAP: <http://www.symas.com>