Creating unique attributes

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This feature enables you to create unique attributes.

Note: On a per attribute basis, language tags are mutually exclusive with unique attributes. If you designate a particular attribute as being a unique attribute, it cannot have language tags associated with it.
When adding or modifying a unique attribute entry, if establishing a unique constraint for any of the listed unique attribute types results in errors, the entry is not added or created in the directory. The problem must be resolved and the command to add or modify must be reissued before the entry can be created or modified. For example, while adding a unique attribute entry to the directory, if establishing a unique constraint on a table for one of the listed unique attribute types failed (that is, because of having duplicate values in the database), a unique attribute entry is not added to the directory. An error DSA is unwilling to perform is issued.
Note: If an entry is created under both cn=localhost and cn=IBMpolicies, the resultant union of these two entries is the consolidation of their unique attributes list. For example, if the attributes uid and employeeNumber are designated as unique in cn=localhost and the attributes uid and telephoneNumber are designated as unique on cn=IBMploicies, the server treats the attributes uid, employeeNumber and telephoneNumber as the unique attributes.

When an application tries to add an entry to the directory with a value for the attribute that duplicates an existing directory entry, an error with result code 20 (LDAP:error code 20 - Attribute or Value Exists) from the LDAP server is issued.

When the server starts, it checks the list of unique attributes and determines if the DB2® constraints exist for each of them. If the constraint does not exist for an attribute because it was removed by the idsbulkload utility or because it was removed manually by the user, it is removed from the unique attributes list and an error message is logged in the error log, ibmslapd.log. For example, if the attribute uid is designated as unique in cn=uniqueattributes, cn=localhost and there is no DB2 constraint for it the following message is logged: 
Values for the attribute UID are not unique.
The attribute UID was removed from the unique attribute 
entry: CN=UNIQUEATTRIBUTES,CN=LOCALHOST