I'm attempting to setup OpenLDAP 2.4.39 on Ubuntu 14.04 LTS and am getting lost on how to switch from the default hdb/bdb backend to mdb.

On http://www.openldap.org/doc/admin24/backends.html#Overview in the 11.4. LMDB section it states:
11.4.2. back-mdb Configuration

Unlike the HDB/BDB backends, the mdb backend can be instantiated with very few configuration lines:
    include ./schema/core.schema

    database  mdb
    directory ./mdb
    suffix    "dc=example,dc=com"
    rootdn    "cn=mdb,dc=example,dc=com"
    rootpw    mdb
    maxsize   1073741824
However it doesn't state where to make these entries.

After installing OpenLDAP through dpkg or apt-get, I have an /etc/ldap/slapd.d/cn=config directory, which contains a file named olcDatabase={1}hdb.ldif. A grep of the directory returns other files containing various entries referencing hdb.

Can anyone advise or provide a link on how to remove the hdb/bdb database configurations and how to use mdb?

I've been googling the better part of this morning and while I have found a few howto's and guide's, they all just have bits of "do this" with no specification of where to do it or in what file. Or am I just missing something in general?

Also, even if i try to reconfigure through #dpkg-reconfigure slapd doesn't ask while in the database selection ? It's having option to select bdb or hdb only.In our organization we are using 389 DS already and once we saw this LMDB feature in openldap, we are planning to migrate slapd.But while starting itself, we are struck.Please help us on the same.If possible include the clear configurarion steps in the official doc.