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Dealing with the impact of data model changes


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.

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 box
Column Description
DataModel/Change Shows the relevant data model and the changes made to the data model.
Level There are three levels of data model changes:
  • Low: The change will lead to the modification of the database schema, but it is perfectly OK.
  • Medium: The change will be reflected in the database schema, but the existing data may cause it to fail.
  • High: 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.

For more information, see Data model changes and their impact levels.

Operation Three options are available:
  • Recreate table: recreate the table to reflect the changes made to the data model. This option is available only if the change level is Medium or High.
  • Apply changes: apply the changes to the data model.
  • Cancel deployment: cancel the deployment of the modified data model.

Once you have made your choice, click OK to validate your changes and close the dialog box.

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