Process Recommendations › Ways to Improve Processes › Specific Encyclopedia Functions › Adding a New Model

Adding a New Model

The following activities can be considered as adding a new model to the encyclopedia:

• Model copy
• Generate new model
• Initial model upload
• Cross copy from another encyclopedia
• Create model from subset

Each of the activities creates objects, associations, properties, and text. The activities place a read lock on the source model to prevent changes to the model while the activity occurs. DB2 locks are acquired during this processing. Periodic commits are executed to alleviate the scope and duration of the DB2 locks.

When you add a new model, all objects, properties, associations and text are added before the DMDL table is updated. Unless the add completes normally and the final step of updating DMDL occurs, orphan objects are left in the database. The orphan objects do not affect other operations, but the incomplete model is unusable. You can clean up the orphan objects with the utility TIECLEAN.

For large models, the overall effect of a failed activity, such as a failed copy, can be substantial. Because a copy does periodic commits, orphan objects are left in the encyclopedia following a failure. For a large model in an encyclopedia where DASD is in short supply, you may need to clean up the orphan objects and REORG the database prior to being able to perform the copy again.