Using the Structure Compare Icebox

This document shows typical scenarios for using the structure compare icebox in XDM.

Comparing the structure of an application model

After designing an application model version, this version represents the situation in which it was created.

Over time the structure of the underlying tables can be changed in various ways. For example:

  • Tables that were referenced in this version no longer exist,

  • References in the database are removed,

  • References are added in the database to define relations to other tables, or

  • Table structures have changed.

All these situations can lead to an incomplete data copy when using this application model version. An application model version is pre-defined, so it is not possible to detect these situations during RLP task execution.

The structure icebox is able to detect such changes. After an application model version is created, it is possible to store the table structures of that version in an icebox generation.

To configure a structure to icebox task for this situation, you only have to define a selection rule for the application model version. Running the structure to icebox task will store the structures in an icebox generation.

To compare the stored structures with the current structures of the application model version, you have to create and execute a structure compare with icebox task, using the same connection as in the structure to icebox task.

To configure the comparison in detail, a structure compare with icebox task template has the same configuration as a structure compare task:

  • Comparable fields define the object parameters to compare,

  • Exclude rules exclude objects from the comparison altogether, and

  • Ignore difference rules allows known differences to be ignored in the structure comparison report.

After the task has been executed, the structure difference report shows the differences between the stored and the current objects. The user can update the application model version, if desired.

Creating new objects from stored structures

The structure compare icebox allows creating new objects in a target environment. If a target object differs from the stored object definition in the icebox generation, it is possible to drop the target object and create a new one which matches the source object.

The structure of an object is stored in an icebox generation of a structure to icebox task template. When comparing this generation with the objects in the target connection, the parameter Generate DDL controls whether new objects are created during task execution. The Drop option controls if missing, different, or all objects are newly created during task execution.

Storing different versions of an object

The structure compare icebox allows the storage of different versions of one object, such as a table, without storing any data. Different structures of one table can be stored in different icebox generations. Choosing the icebox generation in the structure compare with icebox task enables the user to create a specific version of the table in a new environment, as described above.

For more information refer to the structure to icebox task description and to the structure from icebox task description in the reference.