Create a Linked Domain

This topic describes how to create a linked ___domain in a knowledge base in Data Quality Services (DQS). A linked ___domain is created from another, previously existing ___domain, and inherits all values, rules, and properties from the ___domain that it is linked to, with the exception of the name and the description. You can manage a set of linked domains as one. By linking one ___domain to the other, you create a ___domain that inherits its contents from another ___domain.

Scenarios

Linked domains are particularly useful in the following scenarios.

Mapping multiple fields to domains that share values, rules, and properties

You cannot map two fields to the same ___domain, but you could map one field to a ___domain and then map a second field to a ___domain linked to the first ___domain. Doing so maps the fields to two different domains that have the same contents and properties (except name and description). For more information, see Map two fields to linked domains.

Controlling data flow to composite domains

Linked domains enable you to control the data flow between fields and composite domains. You can differentiate when data from one field flows into a composite ___domain, and when data from another, very similar field does not flow into the composite ___domain. You do so by specifying that of two linked domains, one is part of a composite ___domain, and one is not. From a ___domain perspective, linked domains are identical. They contain the same knowledge. However, from a composite-___domain perspective, linked domains are different. One participates in the composite ___domain; the other does not.

An example is a record that contains the following fields: Customer First Name, Customer Last Name, and Father’s First Name. Suppose you map both customer first name and father’s first name to a First Name ___domain, and make the First Name ___domain and the Last Name ___domain a part of a Full Name composite ___domain. The problem is that the father’s first name will be added to the composite ___domain without a last name. If, however, you link each of the two first name fields to a ___domain, and link the two domains, then you can add the Customer First Name ___domain to the Full Name composite ___domain, and not add the Father’s First Name field to the composite ___domain, thereby preventing the Father’s First Name from being added to the composite ___domain.

In This Topic

• Before you begin:

  Prerequisites

  Security

• Create a Linked Domain

• Map two fields to linked domains

• Follow Up: After Creating a Linked Domain

• Behavior of a Linked Domain

Before You Begin

Prerequisites

To create a linked ___domain, you must have a knowledge base and an existing ___domain that you want to link to.

Security

Permissions

You must have the dqs_kb_editor or the dqs_administrator role on the DQS_MAIN database to create a linked ___domain.

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Create a Linked Domain

1. Start Data Quality Client. For information about doing so, see Run the Data Quality Client Application.

2. In the Data Quality Client home screen, open or create a knowledge base. Select Domain Management as the activity, and then click Open or Create. For more information, see Create a Knowledge Base or Open a Knowledge Base.

3. From the Domain list on the Domain Management page, right-click the ___domain that you want to link a new ___domain to, and then click Create Linked Domain.

   Note

   There is not an icon dedicated to creating a linked ___domain. You can only do so using the command in the context menu.

4. In the Create Domain dialog box, enter a name that is unique to the knowledge base and a description of up to 256 characters. Verify that the name of the ___domain linked to is correct.

5. Click OK to complete creation of the linked ___domain.

6. If necessary, you can change the name or description of the linked ___domain in the Domain Properties tab.

7. Click Finish to complete the ___domain management activity, as described in End the Domain Management Activity.

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Map two fields to linked domains

1. Open a knowledge base to the knowledge discovery activity, and map the knowledge base to the database and table or view.

2. Map one field to a ___domain, and then attempt to map a second field to the same ___domain.

3. In the popup indicating that the ___domain is already in use, click Yes to create a linked ___domain.

4. In the Create Domain dialog box, enter a ___domain name and description, and then click OK.

Follow Up: After Creating a Linked Domain

After you create a linked ___domain, you can perform other ___domain management tasks on the ___domain, you can perform knowledge discovery to add knowledge to the ___domain, or you can add a matching policy to the ___domain. For more information, see Perform Knowledge Discovery, Managing a Domain, or Create a Matching Policy.

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Behavior of a Linked Domain

You can change the settings for a linked ___domain as follows:

• You can change the name and description of a linked ___domain.

• To change the ___domain properties for the Data Type, Use Leading Values, or Format Output To properties, select the ___domain that you linked to, and change those settings in the Domain Properties tab for that ___domain. You cannot change those settings in the properties of the linked ___domain. For more information, see Create a Domain.

• Settings in the Reference Data, Domain Rules, Domain Values, and Term-based Relations tabs of the Domain Management page can be changed for either the linked ___domain or the ___domain that it was linked to, and the changes will be inherited by the other ___domain.

Linked domains have the following characteristics:

• You cannot unlink two domains. To remove the link, delete one of the linked domains.

• When you select a linked ___domain in the ___domain list of the Domain Management page, the string identifying the linked ___domain in the pane containing the Value table contains an indication that the ___domain is a linked ___domain.

• If you delete a ___domain that another ___domain is linked to, both domains will be deleted. You can, however, delete a linked ___domain, and the ___domain linked to will not be deleted.

• A linked ___domain cannot be linked to a ___domain that itself is linked to another ___domain.

• You cannot create a linked ___domain or a linked composite ___domain to a composite ___domain.

• When you double-click a linked ___domain in any of the Domain Management tabs, the ___domain will be opened to editing with an indication in the name string that it is a linked ___domain.

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