Data extensions

Before you write extensions, you must define and describe the extensions within the InfoSphere® MDM database, along with the set of condition parameters that must be true for the extension to be run.

When creating an extension, all custom names must be prefixed with a three letter abbreviation followed by an underscore, such as ABC_getItem. These naming guidelines apply to all custom business objects, database tables, and transaction names.

You must define the extensions and their condition parameters from the Data Extension option within InfoSphere MDM Workbench. For more information, see Extension and addition development in the MDM Workbench.

InfoSphere MDM provides two approaches to data extension persistency:
  • Inline extensions persist extension attributes in an existing core database table.
  • Side-table extensions persist the extension attributes in a new extension database table.
The following table provides some guidance to help developers decide which approach to use when implementing data extensions.
Table 1. Data extension considerations
Consideration Side table extensions Inline extensions
Compatibility issues None, assuming naming standards are properly followed. Not supported for second-level extensions (extension-of-extension). None, assuming naming standards are properly followed.
Database I/O performance Inquiry transactions require two database calls: one for the core table, and one for the extension table. When using the Inquiry/Persistence framework, only one database call is required for selecting, inserting, and updating data.
Mapping extension attributes Extension entity objects are mapped to the extension table using IBM® pureQuery Java™ annotations. Extension entity objects are mapped to the same table as the original entity objects were mapped to, using IBM pureQuery Java annotations.
Ability to tune Low High
Data history History for extension columns is kept in its own history table. History for extension columns is kept in the base history table.
Development effort Low Medium. To realize the benefits of the inline extension method, an extra step is required to override the base query to ensure that single INSERT/UPDATE SQL statements are used.

If you have existing manual extensions (extensions done outside of the MDM Workbench), they may require some changes to be compatible with the OSGi framework. For more information, see Overview of OSGi migration.