Limitations of Attribute Uniqueness in Oracle Internet Directory 10g (9.0.4)

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

• 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.