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Thread: HOW TO: Modify a production CDC Solution when source table changes

  1. #1
    Adeeb Mass'ad is offline Support Manager
    Join Date
    Aug 2006
    Jaffa of Nazareth
    Rep Power

    HOW TO: Modify a production CDC Solution when source table changes


    An ETL Solution is in production or in development stage where a source table from the backend database was modified.

    The option of Redeploying the solution is not possible. The user requires manual steps to alter the ETL Solution without performing major changes on the Server (Agent) machine or the Staging Area machine.

    The changes to the source could be one of the followings:
    1. Adding a field to the source table.
    2. Modifying a field's datatype.

    While the Attunity Studio supports adding and removing tables, the process of the redeployment could be impossible at some production sites. The solution may be modified for the long term (or development/testing purposes) and kept without being redeployed, and for the short-term an immediate solution is required.

    Carefully review these steps before applying them:-
    1. Determine a point of time where you have low activity on the system to apply these steps.
    2. Consume all of the changes for the specific table. This is important in order to receive new events with the new structure only.
    3. Deactivate the Solution using the Attunity Studio.
    4. Perform the ALTER TABLE operation on the backend database for the specific table.
    5. On the Router's (Staging Area) machine perform the following steps:-
    • Invoke the Studio's Design perspective.
    • Edit the MetaData of the Router's Datasource.
    • Expand the list and Edit the MetaData for the table.
    • If you are adding a new Column make sure to add it to the end of the COLUMN list. This operation can be also done using the Source view. Make sure you select the CORRECT datatype.
    If you are modifying some datatype, perform the modification making sure to select the corresponding datatype.
    • Save the MetaData.
    Access the directory where the physical Staging Area files are located (DISAM files) and backup the current DAT/IDX/LCK of the specific table.

    Delete the files for the table and Reactivate the Solution.

    The Solution should work as expected. If you face any errors it could be that some events are left unconsumed, and this will confuse the Router since the new column was added. The solution would be to modify the AGENT_CONTEXT in the SA datasource and specify the CONTEXT from the correct point where the new changes are consumed.
    Last edited by Adeeb Mass'ad; 11-01-2007 at 10:33 AM.
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