Managing a Domain
Updated: August 1, 2012
This topic describes the use of domains in Data Quality Services (DQS). A domain contains a semantic representation of the data in a specific field in the data source that is to be analyzed. A domain is part of the knowledge base that you create for a data source, and the knowledge that you build up by analyzing a sample data source, or importing data, is added to the domains defined in the knowledge base. The knowledge in those domains is later used to perform cleansing and matching in a data quality project. Domains are at the core of all activities in Data Quality Services.
A domain is mapped to a data source field, and is populated in the knowledge discovery, domain management, and matching activities. How you load data from the data source and output data in a report is defined in domain properties. When you use a reference data provider to cleanse data, you attach a reference data service to a single or composite domain. You create rules to be applied to your data in a domain, and you can create term-based relations for a domain. You can view and correct data in the domain.
You can also create a composite domain that is comprised of two or more individual domains that each contains knowledge about common data. For more information, see Managing a Composite Domain.
When you create a domain, you have the following options for how to populate the domain from the source data and how to output the domain values. For more information, see Set Domain Properties.
Select the type of the data that you populate the domain with. For information about data types supported for each domain data type, see Supported SQL Server and SSIS Data Types for DQS Domains.
Specify that only leading values, not their synonyms, will be output from the domain.
Specify that domain values be output in a certain format, depending on the data type.
If the data type is a string, you can normalize the string by removing special characters when the string is loaded from the data source into the domain.
If the data type is a string, you can run the DQS Speller to check the syntax, spelling, and sentence structure of the string, and indicate any potential errors in the Domain Values page of Domain Management. This includes specifying the language that the Speller will run in.
If the data type is a string, you can specify that DQS not identify syntax errors when you know that syntax errors will not occur in strings.
Using a domain enables you to do the following:
Create a semantic representation for a data field with a specific data type, specify how the domain is populated, and format the output of the domain
Link a domain to another domain, enabling it to share the same settings and values
Attach a reference data service to a single or composite domain
Change or augment the values in a knowledge base
Use validation and standardization rules
Use relations to correct a term that is part of a value in a domain
Complete, close, or cancel the domain management activity
Building a knowledge base by running knowledge discovery and interactively managing knowledge
Importing knowledge into, or exporting it from, a knowledge base.
Creating a composite domain, and adding knowledge to the domain.