About Metadata on Source Data

Metadata is the data that describes the contents of a given object in a data source or target. For example, metadata for a table indicates the column names and data types for each column.

Before you import source metadata into OWB, first create a module that will contain these metadata definitions. The type of module you create depends on the source from which you are importing metadata. For example, to import metadata definitions from an Oracle database, you create or use an Oracle module. To import metadata definitions from flat files, you create a flat file module.

OWB must have metadata for any source or target object that will be manipulated in your project. The most basic metadata needed by OWB can be created or derived in several ways:

• OWB can directly extract existing metadata from most database sources or targets. For example, when connecting to an Oracle database, OWB queries the database dictionary to extract all needed metadata on tables, views, sequences, dimensions, cubes, data types, PL/SQL packages, and so on.

• You can define and use SQL- or XML-based custom metadata stores to retrieve definitions of source and target objects such as tables and views.

• When you design data objects that do not already exist, the metadata that describes the object is created by the design process.

• For data files extracted from some mainframe sources, OWB can interpret Cobol Copybook files that describes the structure of the data file, and create its source metadata based on that.

• OWB application adapters or application connectors provide additional metadata about ERP and CRM application sources.

The metadata management and reporting features in OWB, and data lineage and impact analysis, depend on, and leverage the metadata about the sources and targets and transformations that move data among them, which accumulates in your OWB projects over time.