databases/openldap-server bdb backend

[Sad Clouds <cryintothebluesky%gmail.com@localhost>]

Hello, question about config options. By default openldap-server
configures bdb backend. As per options.mk:

PKG_SUGGESTED_OPTIONS=          bdb inet6

### NOTE: that option is enabled, because the openldap server needs
###       to have local storage support to work as standalone.

Can anyone explain what this comment means and why it needs bdb? As far
as I understand bdb has been deprecated and mdb backend is now
normally the default. Does this mean bdb can/should be removed from the
suggested options?