SLAPO-UNIQUE(5)               File Formats Manual              SLAPO-UNIQUE(5)

       slapo-unique - Attribute Uniqueness overlay to slapd


       The Attribute Uniqueness overlay can be used with a backend database
       such as slapd-mdb(5) to enforce the uniqueness of some or all
       attributes within a scope. This subtree defaults to all objects within
       the subtree of the database for which the Uniqueness overlay is

       Uniqueness is enforced by searching the subtree to ensure that the
       values of all attributes presented with an add, modify or modrdn
       operation are unique within the scope.  For example, if uniqueness were
       enforced for the uid attribute, the subtree would be searched for any
       other records which also have a uid attribute containing the same
       value. If any are found, the request is rejected.

       The search is performed using the rootdn of the database, to avoid
       issues with ACLs preventing the overlay from seeing all of the relevant
       data. As such, the database must have a rootdn configured.

       These slapd.conf options apply to the Attribute Uniqueness overlay.
       They should appear after the overlay directive.

       unique_uri <[strict ][ignore ]URI[URI...]...>
              Configure the base, attributes, scope, and filter for uniqueness
              checking.  Multiple URIs may be specified within a domain,
              allowing complex selections of objects.  Multiple unique_uri
              statements or olcUniqueURI attributes will create independent
              domains, each with their own independent lists of URIs and
              ignore/strict settings.

              Keywords strict and ignore have to be enclosed in quotes (")
              together with the URI.

              The LDAP URI syntax is a subset of RFC-4516, and takes the form:

              ldap:///[base dn]?[attributes...]?scope[?filter]

              The base dn defaults to that of the back-end database.
              Specified base dns must be within the subtree of the back-end

              If no attributes are specified, the URI applies to all non-
              operational attributes.

              The scope component is effectively mandatory, because LDAP URIs
              default to base scope, which is not valid for uniqueness,
              because groups of one object are always unique.  Scopes of sub
              (for subtree) and one for one-level are valid.

              The filter component causes the domain to apply uniqueness
              constraints only to matching objects.  e.g.
              ldap:///?cn?sub?(sn=e*) would require unique cn attributes for
              all objects in the subtree of the back-end database whose sn
              starts with an e.

              It is possible to assert uniqueness upon all non-operational
              attributes except those listed by prepending the keyword ignore
              If not configured, all non-operational (e.g., system) attributes
              must be unique. Note that the attributes list of an ignore URI
              should generally contain the objectClass, dc, ou and o
              attributes, as these will generally not be unique, nor are they
              operational attributes.

              It is possible to set strict checking for the uniqueness domain
              by prepending the keyword strict.  By default, uniqueness is not
              enforced for null values. Enabling strict mode extends the
              concept of uniqueness to include null values, such that only one
              attribute within a subtree will be allowed to have a null value.
              Strictness applies to all URIs within a uniqueness domain, but
              some domains may be strict while others are not.

       It is not possible to set both URIs and legacy slapo-unique
       configuration parameters simultaneously. In general, the legacy
       configuration options control pieces of a single unfiltered subtree

       unique_base <basedn>
              This legacy configuration parameter should be converted to the
              base dn component of the above unique_uri style of parameter.

       unique_ignore <attribute...>
              This legacy configuration parameter should be converted to a
              unique_uri parameter with ignore keyword as described above.

       unique_attributes <attribute...>
              This legacy configuration parameter should be converted to a
              unique_uri parameter, as described above.

       unique_strict <attribute...>
              This legacy configuration parameter should be converted to a
              strict keyword prepended to a unique_uri parameter, as described

       unique_uri cannot be used with the old-style of configuration, and vice
       versa.  unique_uri can implement everything the older system can do,

       Typical attributes for the ignore ldap:///...  URIs are intentionally
       not hardcoded into the overlay to allow for maximum flexibility in
       meeting site-specific requirements.

       Replication and operations with manageDsaIt control are allowed to
       bypass this enforcement. It is therefore important that all servers
       accepting writes have this overlay configured in order to maintain
       uniqueness in a replicated DIT.

              default slapd configuration file

       slapd.conf(5), slapd-config(5).

OpenLDAP 2.4.48                   2019/07/24                   SLAPO-UNIQUE(5)