I was trying to manual change and HDB LDIF config to BDB and failed to
guess the correct ObjectClass (instead of olcHdbConfig).
Looking at the example in section 5.3:
...It seem the objectclass is olcBdbConfig, but slapd won't accept that
and it isn't present in cn=config/cn=schema.ldif where the other
objectclasses are defined.
Is there a bug in the documentation?