A repository database stores physical data. Such data includes repository type libraries that contain type information or object instance data, and tables used to map or otherwise manage object relationships. In the versions of Microsoft® SQL Server™ 2000 Meta Data Services that Microsoft distributes, storage is provided through SQL Server, SQL Server Runtime Engine, or Microsoft Jet.
Meta Data Services is an installed component of SQL Server. If you are using SQL Server, a repository database already exists for your use. By default, repository tables are predefined in the msdb system database. These tables store data warehousing meta data used by SQL Server and other add-on components.
At a minimum, a repository database includes standard tables that are present in every repository database. Additional tables are created for custom interface definitions. Within its tables, the repository engine stores properties and relationships. For more information about repository tables, see Repository SQL Schema.
If you prefer, you can choose to add your custom meta data to msdb. By keeping all your meta data in one database, you can combine existing definitions in new ways by creating relationships.
Managing Repository Databases
Repository databases are driven by the repository engine, which manages all transactions and determines storage structure. To save space in the database, Meta Data Services can sometimes eliminate redundant data definitions. For example, it may store a single copy of a property value, even if that property value describes many object versions. Similarly, Meta Data Services can sometimes store a single copy of a relationship, even if many different object versions have that relationship.
Repository databases should not be modified directly. Unless you are an expert database programmer or administrator, avoid modifications because you can introduce changes that the repository engine cannot manage.
You can store multiple information models in a single repository database. Connection to a repository database is made using ODBC drivers. To access a specific information model in the tables, use the repository API.
Other Database Types
If you are using Meta Data Services as an add-on component of SQL Server, physical storage of meta data is implemented as a SQL Server database. However, Meta Data Services is also distributed with other Microsoft products. If you are using Meta Data Services as an add-on component of Microsoft Visual Studio®, you can implement data storage as SQL Server tables using Microsoft Jet or SQL Server Runtime Engine. SQL Server Runtime Engine is a SQL Server compatible data engine and it can be used to provide local data storage. For more information about Microsoft Jet or the SQL Server Runtime Engine, see the MSDN® Library at the Microsoft Web site.
Other third-party vendors support Meta Data Services on non-Microsoft database platforms. Future development by third-party vendors will expand the number of database platforms that you can use with Meta Data Services. For more information about third-party support, see Meta Data Services on the SQL Server page at the Microsoft Web site.