# Dealing with the impact of data model changes

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Available in...

* Data Fabric
* MDM Platform

When designing a data model, you can make as many changes as required to the data model before you deploy the modified data model to the MDM server to check if the changes make sense.

Information noteWarning: The data model change will result in a loss of data, including the corresponding logically deleted data records in recycle bin and log of these data records. Because of referential integrity, the change will cascade through the tables defined to have foreign key relationships and result in a loss of their data also.

When you deploy the data model, Talend Studio will perform a series of checks to ensure the validity of the data model.

After the validity checking of a data model, if the changes you made to the data model impact the database schema, for example, adding new elements to one entity in the data model, Talend Studio provides the impact analysis result when you deploy the modified data model to the MDM server which helps you to decide whether to cancel the operation or continue the deployment.

The impact analysis result shows the relevant data model, the description of the changes made to the data model, the level of each change and the operation to be performed.

If a data model change has an impact level of Medium or High and leads to table recreation, the impact analysis result also lists the entities to be dropped and recreated.

![](https://help.qlik.com/talend/en-US/studio-user-guide/Resources/images/studio_mdm-impact_analyis_of_data_model_changes.png)

In this dialog box, you can view the data model changes and select the appropriate operation according to your need.

Columns in the impact analysis results dialog boxColumns in the impact analysis results dialog box

| Column | Description |
| --- | --- |
| DataModel/Change | Shows the relevant data model and the changes made to the data<br>model. |
| Level | There are three levels of data model changes:<br><br><ul> <li> <span>Low</span>: The change will lead to the                                    modification of the database schema, but it is perfectly                                    OK.</li> <li> <span>Medium</span>: The change will be reflected in                                    the database schema, but the existing data may cause it to                                    fail.</li> <li> <span>High</span>: The change cannot be reflected                                    without recreating part of the database schema that corresponds                                    to the data model changes. If you want to change an optional                                    simple type element to a mandatory one, make sure the default                                    value is defined for the element.</li> </ul><br><br>For more information, see [Data model changes and their impact levels](https://help.qlik.com/talend/en-US/studio-user-guide/8.0/data-model-changes-and-their-impact-levels). |
| Operation | Three options are available:<br><br><ul> <li> <span>Recreate table</span>: recreate the table to                                    reflect the changes made to the data model. This option is                                    available only if the change level is                                        <span>Medium</span> or                                    <span>High</span>.</li> <li> <span>Apply changes</span>: apply the changes to the                                    data model. </li> <li> <span>Cancel deployment</span>: cancel the deployment                                    of the modified data model.</li> </ul><br><br>Once you have made your choice, click OK<br>to validate your changes and close the dialog box. |

### In this section

* [Data model changes and their impact levels](https://help.qlik.com/talend/en-US/studio-user-guide/8.0-R2024-06/data-model-changes-and-their-impact-levels)