The Loader provides you with functions for exporting, importing, transporting and formatting data between different data sources and data targets in different granularities.
The Loader distinguishes between application data and metadata.
· Application Data
Application data is the data that
is stored in the database tables.
The Loader writes the application data to a data stream when exporting from
the database system and to the database system when importing from a data
stream.
· Metadata
The database system manages its own
metadata in the database catalog.
For the Loader, the metadata is the metadata of the database system and
additionally the data that describes the application data, database catalog
information and transformations according to the Loader’s
requirements.
The Loader distinguishes between the metadata of the application data, the database catalog and the transformation.
The metadata of the application data (transport type DATA) is defined in the data streams using commands and SQL statements.
If the transformation spans multiple tables, the Loader stores this information in the system tables.
The corresponding data is stored in the database instance in the form of pages or rows, and in a data stream in the non-readable formats PAGES and RECORDS or in the readable formats COMPRESSED, FORMATTED and FORMATTED BINARY .
If the data is transformed in form of rows, then columns of the external data type CHAR with the code attribute ASCII can be transformed to values of data fields with the code attribute ASCII, UCS-2, or UTF-8.
Metadata of the database catalog (transport type CATALOG) describes the structure of the data in the database catalog.
If the transformation spans multiple tables, the Loader stores this information in its system tables.
The corresponding data is stored in the database instance in the form of rows in the system tables and in a data stream in the form of SQL statements for data definition.
The metadata of the transformations (transport types CONFIGURATION and PACKAGE) is declared in the form of commands or in the form of Loader-specific system tables.
This metadata describes the configuration and the runtime behavior of the transformations that span multiple tables.
The corresponding data, such as user names and table names, is stored, sorted by referential constraint conditions.
In the database instance, the data is stored in the form of rows in the system tables in a data stream in the readable format COMPRESSED.
See also: