.TH SLAPO-UNIQUE 5 "RELEASEDATE" "OpenLDAP LDVERSION"
-.\" Copyright 2004-2005 The OpenLDAP Foundation All Rights Reserved.
+.\" Copyright 2004-2011 The OpenLDAP Foundation All Rights Reserved.
.\" Copying restrictions apply. See COPYRIGHT/LICENSE.
.\" $OpenLDAP$
.SH NAME
-slapo-unique \- Attribute Uniqueness overlay
+slapo\-unique \- Attribute Uniqueness overlay to slapd
.SH SYNOPSIS
ETCDIR/slapd.conf
.SH DESCRIPTION
The Attribute Uniqueness overlay can be used with a backend database such as
-.BR slapd-bdb (5)
-to enforce the uniqueness of some or all attributes within a subtree. This
-subtree defaults to the base DN of the database for which the Uniqueness
-overlay is configured.
+.BR slapd\-bdb (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 configured.
.LP
Uniqueness is enforced by searching the subtree to ensure that the values of
all attributes presented with an
.B modify
or
.B modrdn
-operation are unique within the subtree.
+operation are unique within the scope.
For example, if uniqueness were enforced for the
.B uid
attribute, the subtree would be searched for any other records which also
.B uid
attribute containing the same value. If any are found, the request is
rejected.
+.LP
+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.
.SH CONFIGURATION
These
.B slapd.conf
options apply to the Attribute Uniqueness overlay.
They should appear after the
.B overlay
-directive and before any subsequent
-.B database
directive.
.TP
-.B unique_base <basedn>
-Configure the subtree against which uniqueness searches will be invoked.
+.B 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
+.B unique_uri
+statements or
+.B olcUniqueURI
+attributes will create independent domains, each with their own
+independent lists of URIs and ignore/strict settings.
+
+The LDAP URI syntax is a subset of
+.B RFC-4516,
+and takes the form:
+
+ldap:///[base dn]?[attributes...]?scope[?filter]
+
The
-.B basedn
-defaults to the base DN of the database for which uniqueness is configured.
-.TP
-.B unique_ignore <attribute...>
-Configure one or more attributes for which uniqueness will not be enforced.
-If not configured, all non-operational (eg, system) attributes must be
+.B base dn
+defaults to that of the back-end database.
+Specified base dns must be within the subtree of the back-end database.
+
+If no
+.B attributes
+are specified, the URI applies to all non-operational attributes.
+
+The
+.B scope
+component is effectively mandatory, because LDAP URIs default to
+.B base
+scope, which is not valid for uniqueness, because groups of one object
+are always unique. Scopes of
+.B sub
+(for subtree) and
+.B one
+for one-level are valid.
+
+The
+.B filter
+component causes the domain to apply uniqueness constraints only to
+matching objects. e.g.
+.B ldap:///?cn?sub?(sn=e*)
+would require unique
+.B cn
+attributes for all objects in the subtree of the back-end database whose
+.B sn
+starts with an e.
+
+It is possible to assert uniqueness upon all non-operational
+attributes except those listed by prepending the keyword
+.B ignore
+If not configured, all non-operational (e.g., system) attributes must be
unique. Note that the
-.B unique_ignore
-list should generally contain the
+.B attributes
+list of an
+.B ignore
+URI should generally contain the
.BR objectClass ,
.BR dc ,
.B ou
.B 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
+.B strict.
+By default, uniqueness is not enforced
+for null values. Enabling
+.B 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.
+.LP
+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 domain.
+.TP
+.B unique_base <basedn>
+This legacy configuration parameter should be converted to the
+.B base dn
+component of the above
+.B unique_uri
+style of parameter.
+.TP
+.B unique_ignore <attribute...>
+This legacy configuration parameter should be converted to a
+.B unique_uri
+parameter with
+.B ignore
+keyword as described above.
.TP
.B unique_attributes <attribute...>
-Specify one or more attributes for which uniqueness will be enforced.
-If not specified, all attributes which are not operational (eg, system
-attributes such as
-.B entryUUID )
-or specified via the
-.B unique_ignore
-directive above must be unique within the subtree.
+This legacy configuration parameter should be converted to a
+.B unique_uri
+parameter, as described above.
.TP
.B unique_strict
-By default, uniqueness is not enforced for null values. Enabling
-.B unique_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.
+This legacy configuration parameter should be converted to a
+.B strict
+keyword prepended to a
+.B unique_uri
+parameter, as described above.
.SH CAVEATS
.LP
-The search key is generated with attributes that are non-operational, not
-on the
-.B unique_ignore
-list, and included in the
-.B unique_attributes
-list, in that order. This makes it possible to create interesting and
-unusable configurations. Usually only one of
-.B unique_ignore
-or
-.B unique_attributes
-should be configured; use
-.B unique_ignore
-if the majority of attributes should be unique, and use
-.B unique_attributes
-if only a small set of attributes should be unique.
+.B unique_uri
+cannot be used with the old-style of configuration, and vice versa.
+.B unique_uri
+can implement everything the older system can do, however.
.LP
Typical attributes for the
-.B unique_ignore
-directive are intentionally not hardcoded into the overlay to allow for
+.B ignore ldap:///...
+URIs are intentionally not hardcoded into the overlay to allow for
maximum flexibility in meeting site-specific requirements.
+.LP
+Replication and operations with
+.B 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.
.SH FILES
.TP
ETCDIR/slapd.conf
default slapd configuration file
.SH SEE ALSO
-.BR slapd.conf (5).
+.BR slapd.conf (5),
+.BR slapd\-config (5).
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