18 Managing Attribute Uniqueness Constraint Entries

This chapter explains attribute uniqueness in Oracle Internet Directory. It contains these topics:

• Section 18.1, "Introduction to Managing Attribute Uniqueness Constraint Entries"

• Section 18.2, "Specifying Attribute Uniqueness Constraint Entries"

• Section 18.3, "Managing an Attribute Uniqueness Constraint Entry by Using Oracle Directory Services Manager"

• Section 18.4, "Managing an Attribute Uniqueness Constraint Entry by Using the Command Line"

18.1 Introduction to Managing Attribute Uniqueness Constraint Entries

When you use the LDAP tools, the attribute uniqueness feature prevents duplication of attribute values, both when adding and modifying them. For example, it prevents you from assigning to a new employee an identifier already assigned to another employee. Instead, the directory server terminates the operation and returns an error message.

You can define attribute uniqueness:

• Across the entire directory

  For example, to ensure that every entry in your directory that includes a mail attribute has a unique value for that attribute, you create an instance of attribute uniqueness associated with mail.

• Across one subtree for each attribute

  For example, suppose that MyCompany hosts the directories for SubscriberCompany1 and SubscriberCompany2. You can choose to enforce attribute uniqueness in SubscriberCompany1 only.

• Across one object class

  For example, suppose that ID is an attribute in both the machine object class and the person object class. If attribute uniqueness is enabled, then the directory server prevents you from adding either two machines or two people with the same ID. You can, however, add a machine ID attribute that has the same value as an existing person ID attribute. Similarly, you can add a person ID attribute that has the same value as an existing machine ID attribute.

Note:

The LDAP tools support attribute uniqueness. The bulk tools do not.

To implement attribute uniqueness, you create an attribute uniqueness constraint entry in which you provide values for the attributes in Table 18-1.

Attribute uniqueness constraint entries are stored under cn=unique,cn=Common,cn=Products,cn=OracleContext.

Table 18-1 Attribute Uniqueness Constraint Entry

Attribute Name	Mandatory?	Valid Value	Default Value	Default Effect
orcluniqueattrname	Yes	Any string	N/A	N/A
orcluniquescope	No	One of the following: base: Searches the root entry only onelevel: Searches one level only sub: Searches the entire directory	sub	Searches the entire directory
orcluniqueenable	No	Either 0 (disable) or 1 (enable)	0	Disables attribute uniqueness
orcluniquesubtree	No	Any string	" "	Searches the entire directory
orcluniqueobjectclass	No	Any string	" "	Searches all object classes

When you have created the entry and specified the attributes, before it performs an operation, the directory server:

• Uses the attribute uniqueness constraint to check all update operations

• Determines whether the operation applies to a monitored attribute, subtree, or object class

If an operation applies to a monitored attribute, suffix, or object class, and would cause two entries to have the same attribute value, then the directory server terminates the operation and returns a constraint violation error message to the client.

Note:

The attribute uniqueness feature works on indexed attributes only.

When an attribute uniqueness constraint is present in the Oracle Internet Directory replication environment, be careful about configuring the attribute uniqueness constraints on each server.

This section contains these topics:

• Section 18.1, "Simple Replication Scenario"

• Section 18.1, "Multimaster Replication Scenario"

Simple Replication Scenario

Because all modifications by client applications are performed on the supplier server, the attribute uniqueness constraint should be enabled on that server. It is not necessary to enable the attribute uniqueness constraint on the consumer server. Enabling the attribute uniqueness constraint on the consumer server does not prevent the directory server from operating correctly, but it can cause a performance degradation.

Multimaster Replication Scenario

In a multimaster replication scenario, nodes serve as both suppliers and consumers of the same replica. Multimaster replication uses a loosely consistent replication model.

Enabling an attribute uniqueness constraint on one of the servers does not ensure that attribute values are unique across both masters at any given time. Enabling an attribute uniqueness constraint on only one server can cause inconsistencies in the data held on each replica.

The attribute uniqueness constraint must be enabled on both masters. However, there may still be an inconsistent state. For example, in both masters we can successfully modify entries to the same attribute value. However, when the changes are later replicated to the other node, the conflict becomes apparent. You must take this type of conflict resolution into consideration as well, deciding whether conflict resolution should be the replication server's responsibility.

18.2 Specifying Attribute Uniqueness Constraint Entries

Attribute uniqueness constraint entries are stored under cn=unique,cn=Common,cn=Products,cn=OracleContext.

This section describes and gives examples of rules you follow when creating attribute uniqueness constraints. It contains these topics:

• Section 18.2.1, "Specifying Multiple Attribute Names in an Attribute Uniqueness Constraint"

• Section 18.2.2, "Specifying Multiple Subtrees in an Attribute Uniqueness Constraint"

• Section 18.2.3, "Specifying Multiple Scopes in an Attribute Uniqueness Constraint"

• Section 18.2.4, "Specifying Multiple Object Classes in an Attribute Uniqueness Constraint"

• Section 18.2.5, "Specifying Multiple Subtrees, Scopes, and Object Classes in an Attribute Uniqueness Constraint"

To understand the examples in this section, refer to Figure 18-1.

Figure 18-1 Example of a Directory Information Tree

Description of "Figure 18-1 Example of a Directory Information Tree"

18.2.1 Specifying Multiple Attribute Names in an Attribute Uniqueness Constraint

When multiple attribute uniqueness constraints have different values in orcluniqueattrname, their effects are independent of each other.

For example, suppose that a user defines two attribute uniqueness constraints as follows:

Constraint1:

orcluniqueattrname: employee_id

Constraint2:

orcluniqueattrname: email_id

In this example, Constraint1 and Constraint2 enforce uniqueness on the specified attribute within their own attribute uniqueness scopes. Constraint1 and Constraint2 are independent of each other.

18.2.2 Specifying Multiple Subtrees in an Attribute Uniqueness Constraint

When multiple attribute uniqueness constraints have the same values in orcluniqueattrname, orcluniquescope and orcluniqueobjectclass, but different values in orcluniquesubtree, the subtree scopes specified by those attribute uniqueness constraints are checked individually.

For example, refer to Figure 18-1. Suppose that a user defines two attribute uniqueness constraints as follows:

Constraint1:

orcluniqueattrname: employee_id
orcluniquesubtree: o=sales, c=us, cn=root
orcluniquescope: onelevel

Constraint2:

orcluniqueattrname: employee_id
orcluniquesubtree: o=hr, c=euro, cn=root
orcluniquescope: onelevel

In this example, the attribute uniqueness on employee_id is enforced against all entries under subtree o=sales,c=us,cn=root. Attribute uniqueness on employee_id is also enforced against all entries under o=hr,c=euro,cn=root independent of the entries under the subtree o=sales,c=us,cn=root—that is, the directory server enforces the unique value of the employee_id attribute for employee3 and employee4. Unique employee_id is enforced for employee7 and employee8 as well while employee7 could have the same employee_id as employee4.

18.2.3 Specifying Multiple Scopes in an Attribute Uniqueness Constraint

When multiple attribute uniqueness constraints have the same values in orcluniqueattrname, orcluniquesubtree and orcluniqueobjectclass, but different values in orcluniquescope, the attribute uniqueness constraint with the largest search scope takes effect.

For example, referring to Figure 18-1, suppose that a user defines two attribute uniqueness constraints as follows:

Constraint1:

orcluniqueattrname: employee_id
orcluniquesubtree: c=us, cn=root
orcluniquescope: onelevel

Constraint2:

orcluniqueattrname: employee_id
orcluniquesubtree: c=us, cn=root
orcluniquescope: sub

In this example, the attribute uniqueness on employee_id is enforced against all entries under the subtree c=us,cn=root and the entry c=us,cn=root itself. Note that this is the same as if the user had defined only Constraint2.

18.2.4 Specifying Multiple Object Classes in an Attribute Uniqueness Constraint

When multiple attribute uniqueness constraints have the same values in orcluniqueattrname, orcluniquesubtree, and orcluniquescope, but different values in orcluniqueobjectclass, then the union of attributes belonging to those object classes is checked.

For example, look at Figure 18-1. Suppose that a user defines two attribute uniqueness constraints as follows:

Constraint1:

orcluniqueattrname: employee_id
orcluniquesubtree: c=us, cn=root
orcluniqueobjectclass: person

Constraint2:

orcluniqueattrname: employee_id
orcluniquesubtree: c=us, cn=root

In this example, the attribute uniqueness on employee_id is enforced against all entries under the subtree c=us,cn=root and the entry c=us,cn=root itself, no matter what object class those entries belong to. Note that Constraint2 specifies no orcluniqueobjectclass attribute, which is the same as specifying all object classes.

18.2.5 Specifying Multiple Subtrees, Scopes, and Object Classes in an Attribute Uniqueness Constraint

When multiple attribute uniqueness constraints have the same values in orcluniqueattrname, but different values in orcluniquesubtree, orcluniquescope, and orcluniqueobjectclass, the entries that belong to the attribute uniqueness scopes of different constraints are checked individually.

For example, referring to Figure 18-1, suppose that a user defines two attribute uniqueness constraints as follows:

Constraint1:

orcluniqueattrname: employee_id
orcluniquesubtree: o=sales, c=us, cn=root
orcluniquescope: onelevel
orcluniqueobjectclass: person

Constraint2:

orcluniqueattrname: employee_id
orcluniquesubtree: c=euro, cn=root
orcluniquescope: sub
orcluniqueobjectclass: organization

In this example, the attribute uniqueness on employee_id is enforced against each of the following independent of each other:

• All entries one level under the entry o=sales,c=us,cn=root with the object class person

• All entries under subtree c=euro,cn=root and the entry c=euro,cn=root itself with the object class organization

18.3 Managing an Attribute Uniqueness Constraint Entry by Using Oracle Directory Services Manager

You can manage an attribute uniqueness constraint policy by using Oracle Directory Services Manager.

18.3.1 Creating an Attribute Uniqueness Constraint Entry by Using ODSM

1. Invoke Oracle Directory Services Manager and connect to the Oracle Internet Directory server as described in Section 7.4.5, "Invoking Oracle Directory Services Manager."

2. Select Advanced from the task selection bar.

3. Expand Attribute Uniqueness in the left pane.

4. On the toolbar, choose the Create an attribute uniqueness constraint icon. This displays the New Constraint window.

5. In the New Constraint dialog box, enter values in the text fields and select the Unique Attribute Scope. You can click Browse to select the Unique Attribute Subtree.

6. If you want to enable the constraint now, click Enable Unique Attribute.

7. Choose OK. The entry you just created appears in the list of attribute uniqueness constraint entries in the left panel.

8. Click Apply to apply this constraint or Revert to revert to the state before you created the new entry.

18.3.2 Modifying an Attribute Uniqueness Constraint Entry by Using ODSM

1. Invoke Oracle Directory Services Manager and connect to the Oracle Internet Directory server as described in Section 7.4.5, "Invoking Oracle Directory Services Manager."

2. Select Advanced from the task selection bar.

3. Expand Attribute Uniqueness in the left pane.

4. Select an existing uniqueness constraint. This displays the General tab of the Attribute Uniqueness Constraint window.

5. Enter or modify values.

6. If you want to enable the constraint now, click Enable Unique Attribute.

7. Click Apply to apply this change or Revert to revert to the state before you modified the entry.

18.3.3 Deleting an Attribute Uniqueness Constraint Entry by Using ODSM

To delete an attribute uniqueness constraint policy:

1. Invoke Oracle Directory Services Manager and connect to the Oracle Internet Directory server as described in Section 7.4.5, "Invoking Oracle Directory Services Manager."

2. Select Advanced from the task selection bar.

3. Expand Attribute Uniqueness in the left pane.

4. In the left panel, select the attribute uniqueness constraint entry you want to delete.

5. Choose the Delete icon, then, when prompted, confirm the deletion. The entry you deleted no longer appears in the list of attribute uniqueness constraint entries in the left panel.

6. Click Apply to apply this change or Revert to revert to the state before you deleted the entry.

18.4 Managing an Attribute Uniqueness Constraint Entry by Using the Command Line

You can manage an attribute uniqueness constraint policy by using the command line.

18.4.1 Creating Attribute Uniqueness Across a Directory by Using Command-Line Tools

To create an instance of attribute uniqueness across an entire directory, specify an attribute name for which you want to enforce value uniqueness.

For example, to make employee identifiers unique for all US employees at MyCompany, you would follow these steps:

1. Create an attribute uniqueness constraint entry (in LDIF format) as follows:

   dn: cn=constraint1, cn=unique, cn=common, cn=products, cn=oraclecontext
   objectclass: orclUniqueConfig
   orcluniqueattrname: employeenumber
   orcluniquesubtree: o=MyCompany, c=US
   orcluniqueobjectclass: person
   

2. Apply the attribute uniqueness feature by loading the attribute uniqueness constraint entry as follows:

   ldapadd –h host -p port -D DN -q -f constraint1.ldif
   

3. Restart the directory server.

Example:

The following LDIF file, uniquenessConstraint.ldif, specifies a uniqueness constraint for the orclcommonusernickname attribute:

# Use this LDIF file to set up a uniqueness constraint on the nickname 
# attribute within the user search base.
# Before running the script, change the following parameters in the LDIF file.
#  <userid_attribute> -  Specify the name of the attribute that holds the user
# id. This value should be the same as the orclcommonusernickname attribute
# configured for the realm.#  <dn _f_user_serach_base> - Specify the user search base in which the
# uniqueness constraint should be enforced.
#
dn: cn=<userid_attribute> ,cn=unique,cn=common,cn=Products, cn=OracleContext
changetype: add
objectclass: orclUniqueConfig
orcluniqueattrname: <userid _ttribute>
orcluniquesubtree: <dn_of_user_search_base>
orcluniqueenable:1 

18.4.2 Creating Attribute Uniqueness Across One Subtree by Using Command-Line Tools

To create an instance of attribute uniqueness across one or more subtrees, specify:

• An attribute name for which you want to enforce value uniqueness

• Subtree locations under which you want the uniqueness constraint to be enforced

For example, suppose that MyCompany hosts the directories for SubscriberCompany1 and SubscriberCompany2, and you want to enforce the uniqueness of the employee identifier attribute in SubscriberCompany1 only. When you add an entry such as uid=dlin,ou=people,o=SubscriberCompany1,dc=MyCompany,
dc=com, you must enforce uniqueness only in the o=SubscriberCompany1,dc=MyCompany,dc=com subtree. Do this by listing the DN of the subtree explicitly in the attribute uniqueness constraint configuration.

In this case, the LDIF file would look like this:

dn: cn=constraint1, cn=unique, cn=common, cn=products, cn=oraclecontext
objectclass: orclUniqueConfig
orcluniqueattrname: employeenumber
orcluniquesubtree: o=SubscriberCompany1,dc=MyCompany,     dc=com

18.4.3 Creating Attribute Uniqueness Across One Object Class by Using Command-Line Tools

To create an instance of attribute uniqueness across one object class, specify:

• An attribute name for which you want to enforce value uniqueness

• Object class name

In this case, the LDIF file would look like this:

dn: cn=constraint1, cn=unique, cn=common, cn=products, cn=oraclecontext
objectclass: orclUniqueConfig
orcluniqueattrname: employeenumber
orcluniqueobjectclass: person

Use ldapadd to add the entry.

ldapadd -D "cn=orcladmin" -q -p port -D user -f file_name

18.4.4 Modifying Attribute Uniqueness Constraint Entries by Using Command-Line Tools

To modify an attribute uniqueness entry, use create an LDIF file for the entry, then use ldapmodify to upload it into the directory.

For example, suppose there is an existing attribute uniqueness constraint entry:

dn: cn=constraint1, cn=unique, cn=common, cn=products, cn=oraclecontext
objectclass: orclUniqueConfig
orcluniqueattrname: employeenumber
orcluniquesubtree: o=MyCompany, c=US
orcluniqueobjectclass: person

To enforce the constraint against c=US, instead of o=MyCompany, you would perform these steps:

1. Create an LDIF entry to change the orcluniquenesssubtree:

   dn: cn=constraint1, cn=unique, cn=common, cn=products, cn=oraclecontext
   changetype: modify
   replace: orcluniquesubtree
   orcluniquesubtree: o=Oracle Corporation, c=US
   

2. Use ldapmodify to apply the change to directory server.

   ldapmodify -D "cn=orcladmin" -q -p port -D user -f file_name
   

3. Restart the directory server to effect this change.

18.4.5 Deleting Attribute Uniqueness Constraint Entries by Using Command-Line Tools

Use the ldapdelete command-line tool to delete an attribute uniqueness constraint policy.

1. Remove the attribute uniqueness constraint entry from the directory by using ldapdelete.

   ldapdelete -D "cn=orcladmin" -q -p port -D bind_DN \   
    "cn=constraint1,cn=unique,cn=common,cn=products,cn=oraclecontext"
   

2. Restart the directory server to effect this change.

18.4.6 Enabling and Disabling Attribute Uniqueness by Using Command-Line Tools

You can enable or disable attribute uniqueness for an existing attribute uniqueness constraint entry.

To enable attribute uniqueness for an existing attribute uniqueness constraint entry:

1. Set the orcluniqueenable attribute to 1 by using ldapmodify.

2. Restart the directory server to enable the policy.

To disable attribute uniqueness:

1. Set the orcluniqueenable attribute to 0 by using ldapmodify.

2. Restart the directory server to disable the policy.