Understanding Data dictionary

What the data dictionary is

The data dictionary is a collection of information about object types and their properties.
The information is stored in internal data types and made visible to users and applications through the process of publishing the data.

EMC Documentum Content Server Version 6.5 Fundamentals

The data dictionary is the mechanism you can use to localize Content Server. The data dictionary supports multiple locales. A data dictionary locale represents a specific geographic region or linguistic group.

Publishing the data dictionary

Data dictionary information is stored in repository objects that are not visible or available to users or applications. To make the data dictionary information available, it must be published. Publishing the data dictionary copies the information in the internal objects
into three kinds of visible objects:

  • dmi_dd_attr_info
    Contains the published data dictionary information for a property.
  • dmi_dd_common_info
    Contains the published data dictionary information that an object type and property have in common.
  • dmi_dd_type_info
    Contains the published data dictionary information for an object type.

For example, if a site has two locales, German and English installed, there will be two dd_type_info objects for each object type—one for the German locale and one for the English locale. Similarly, there will be two dd_attr_info objects for each property—one for the German locale and one for the English locale. However, there will be only one dd_common_info object for each object type and property because that object stores the information that is common across all locales.

Retrieving data dictionary information

You can retrieve data dictionary information using DQL queries or a DFC method. Using DQL lets you obtain multiple data dictionary values in one query. However, the queries are run against the current dmi_dd_type_info, dmi_dd_attr_info, and dmi_dd_common_info objects. Consequently, a DQL query may not return the most current data dictionary information if there are unpublished changes in the information.
Neither DQL or DFC queries return data dictionary information about new object types or added properties until that information is published, through an explicit publishDataDictionary method (in the IDfSession interface) or through the scheduled execution of the Data Dictionary Publisher job.

17. April 2012Permalink