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Oracle® Internet Directory Administrator's Guide,
10g Release 2 (10.1.2) B14082-02 |
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Oracle® Internet Directory Administrator's Guide,
10g Release 2 (10.1.2) B14082-02 |
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This chapter explains attribute uniqueness in Oracle Internet Directory. It contains these topics:
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. However, a machine ID attribute can have the same value as a person ID attribute.
To implement attribute uniqueness, you create an attribute uniqueness constraint entry in which you provide values for the attributes in Table 7-1.
Table 7-1 Attribute Uniqueness Constraint Entry
| Attribute Name | Mandatory? | Valid Value | Default Value | Default Effect |
|---|---|---|---|---|
|
Yes |
Any string |
N/A |
N/A |
|
|
No |
One of the following:
|
|
Searches the entire directory |
|
|
No |
Either |
|
Disables attribute uniqueness |
|
|
No |
Any string |
|
Searches the entire directory |
|
|
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.
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Note: The attribute uniqueness feature works on indexed attributes only. |
This section describes and gives examples of rules you follow when creating attribute uniqueness constraints. It contains these topics:
Specifying Multiple Attribute Names in an Attribute Uniqueness Constraint
Specifying Multiple Subtrees in an Attribute Uniqueness Constraint
Specifying Multiple Scopes in an Attribute Uniqueness Constraint
Specifying Multiple Object Classes in an Attribute Uniqueness Constraint
Specifying Multiple Subtrees, Scopes, and Object Classes in an Attribute Uniqueness Constraint
To understand the examples in this section, refer to Figure 7-1.
Figure 7-1 Example of a Directory Information Tree
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.
When multiple attribute uniqueness constraints have the same values in orcluniqueattrname, orcluniquescope and orcluniqueobjectclass, but different values in orcluniquesubtree, the union of subtree scopes specified by those attribute uniqueness constraints is checked.
For example, refer to Figure 7-1. 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 and o=hr,c=euro,cn=root—that is, the directory server enforces the unique value of the employee_id attribute for employee3, employee4, employee7 and employee8.
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 7-1, 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.
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 7-1. 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.
When multiple attribute uniqueness constraints have the same values in orcluniqueattrname, but different values in orcluniquesubtree, orcluniquescope, and orcluniqueobjectclass, the union of entries that belong to the attribute uniqueness scopes of different constraints are checked.
For example, referring to Figure 7-1, 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 the following:
All entries under the subtree o=sales,c=us,cn=root where their object class belongs to person
All entries under subtree c=euro,cn=root and the entry c=euro,cn=root itself where their object class belongs to organization
This section contains these topics:
Attribute uniqueness constraint entries are stored under cn=unique,cn=Common,cn=Products,cn=OracleContext.
You can use Oracle Directory Manager to create, modify, and delete attribute uniqueness constraint entries.
In the navigator pane, expand in succession Oracle Internet Directory Servers, directory server instance, and Attribute Uniqueness Management. The Attribute Uniqueness Management window displays a list of existing attribute uniqueness constraint entries in the right pane.
On the toolbar, choose Create. This displays the New Constraint window.
In the New Constraint dialog box, enter values for the fields. These are described in Table A-8.
Choose OK. This returns you to the Attribute Uniqueness Management window. The entry you just created appears in the list of attribute uniqueness constraint entries.
Choose Apply.
To modify an attribute uniqueness constraint entry:
In the navigator pane, expand in succession Oracle Internet Directory Servers, directory server instance, and Attribute Uniqueness Management. The Attribute Uniqueness Management window displays a list of existing attribute uniqueness constraint entries in the right pane.
In the Attribute Uniqueness Management window, select the attribute uniqueness constraint entry you want to modify, then choose Edit. The Attribute Uniqueness Constraint window for that attribute appears.
In the Attribute Uniqueness Constraint window, enter your modifications in the appropriate fields, then choose OK. This returns you to the Attribute Uniqueness Management window.
Choose Apply.
To delete an attribute uniqueness constraint policy:
In the navigator pane, expand in succession Oracle Internet Directory Servers, directory server instance, and Attribute Uniqueness Management. The Attribute Uniqueness Management window displays a list of existing attribute uniqueness constraint entries in the right pane.
In the Attribute Uniqueness Management window, select the attribute uniqueness constraint entry you want to delete, then choose Edit. The Attribute Uniqueness Constraint window for this attribute appears.
Choose Delete, then, when prompted, confirm the deletion. This returns you to the Attribute Uniqueness Constraint window. The entry you deleted no longer appears in the list of attribute uniqueness constraint entries.
This section contains these topics:
Enabling and Disabling Attribute Uniqueness by Using Command-Line Tools
Creating Attribute Uniqueness Constraint Entries by Using Command-Line Tools
Modifying Attribute Uniqueness Constraint Entries by Using Command-Line Tools
Deleting Attribute Uniqueness Constraint Entries 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:
Set the orcluniqueenable attribute to 1 by using ldapmodify.
Restart the directory server to enable the policy.
To disable attribute uniqueness:
Set the orcluniqueenable attribute to 0 by using ldapmodify.
Restart the directory server to disable the policy.
To enable attribute uniqueness, specify an attribute uniqueness constraint entry with the attributes listed in Table 7-1.
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:
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 orcleuniqueobjectclass: person
Apply the attribute uniqueness feature by loading the attribute uniqueness constraint entry as follows:
ldapadd –h host -p port -D DN -w password -f constraint1.dat
Restart the directory server.
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
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 orcleuniqueobjectclass: person
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 orcleuniqueobjectclass: person
To enforce the constraint against c=US, instead of o=MyCompany, you would perform these steps:
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
Use ldapmodify to apply the change to directory server.
ldapmodify -p port -D user -w password -f file_name
Restart the directory server to effect this change.
Use the ldapdelete command-line tool to delete an attribute uniqueness constraint policy.
Remove the attribute uniqueness constraint entry from the directory by using ldapdelete.
ldapdelete -p port -D bind_DN -w password \ "cn=constraint1,cn=unique,cn=common,cn=products,cn=oraclecontext"
Restart the directory server to effect this change.
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:
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.
