The monitor backend to slapd(8) is not an actual database; if enabled, it is automatically generated and dynamically maintained by slapd with information about the running status of the daemon.
To inspect all monitor information, issue a subtree search with base cn=Monitor, requesting that attributes "+" and "*" are returned. The monitor backend produces mostly operational attributes, and LDAP only returns operational attributes that are explicitly requested. Requesting attribute "+" is an extension which requests all operational attributes.
See the Monitoring section.