Preserving and Removing Downstream Expressions FAQS

1. What are downstream expressions in ODI 12c?
• Downstream expressions refer to the data mappings, transformations, or any logic applied between components in a mapping. These expressions are created when you connect or modify components in the mapping.
2. What happens when I delete a component in ODI 12c?
• When you delete a component, a confirmation dialog appears. This dialog includes a checkbox that allows you to decide whether to preserve or remove any downstream expressions related to the deleted component.
3. By default, does ODI preserve or remove downstream expressions when I delete a component?
• By default, ODI preserves downstream expressions when you delete a component. This means the data mappings and transformations that were applied will remain intact.
4. How can I remove downstream expressions when deleting a component?
• If you want to remove downstream expressions when deleting a component, simply uncheck the "Preserve downstream expressions" checkbox in the confirmation dialog before confirming the deletion.
5. Why would I want to preserve downstream expressions when deleting a component?
• Preserving downstream expressions allows you to make changes to a mapping without losing previously created mappings or transformations. For example, if you need to add a filter between source and target datastores, you can delete the connection but preserve the attribute mappings that were already defined.
6. Can I modify downstream expressions after deleting a component?
• Yes, after deleting a component and preserving downstream expressions, you can continue modifying the downstream expressions, such as adding new components or adjusting mappings as necessary.
7. What is an example of when I would use the "Preserve downstream expressions" option?
• For example, if you have a source datastore mapped to a target datastore and you realize you need to filter the source data, you can delete the connection between the source and target, preserve the expressions (i.e., the attribute mappings), and then insert a filter component in the middle. The mappings won’t be lost.
8. Can I remove downstream expressions if I no longer need them?
• Yes, if you no longer need the downstream expressions (such as mappings or transformations), you can choose to remove them by unchecking the option in the confirmation dialog when deleting a component.
9. Will preserving downstream expressions affect the integrity of my data flow?
• No, preserving downstream expressions ensures that the integrity of your data flow is maintained. The existing mappings or transformations will stay in place and continue functioning as they did before, even if you change other components in the mapping.
10. What happens if I accidentally delete a component but need to restore the downstream expressions?
• If you delete a component and uncheck the option to preserve downstream expressions, you may lose the mappings and transformations. To avoid this, always check the box to preserve expressions or manually recreate the logic if needed.