IMS CDC Connector Guide > IMS CDC administration > Handling changes to extraction maps
  

Handling changes to extraction maps

If you make table definition changes that affect the columns from which change data is captured, perform this procedure to enable PowerExchange to switch to the updated database definition, while preserving access to previously captured data.
If you add or drop columns in an IMS source database, you must create a new capture registration. PowerExchange generates an associated extraction map by default. Use the generated extraction map instead of creating a user-defined extraction map. PowerExchange on the IMS CDC Connector system retrieves information from the newly generated extraction map.
Note: You do not need to perform these steps if you selectively capture change data for a subset of columns, and none of the selected columns are affected by the database definition changes.
    1Stop all transactions, applications, and other activity that update the source database.
    2Verify that any change data that was captured under the current database definition has completed IMSe CDC Connector extraction processing. Then stop all mapping tasks that extract change data for the database.
    3Shut down the PowerExchange Logger on the z/OS system.
    4In the PowerExchange Navigator, delete the original capture registration and extraction map.
    5Use DDL to make the changes to the database.
    6In the PowerExchange Navigator, create a new capture registration that reflects the metadata changes and set its status to Active. A corresponding extraction map is generated.
    Tip: Use the original registration name so that you do not need to the edit the map name that is used by the workflows that contain the changed source database.
    7Warm start the PowerExchange Logger for Linux, UNIX, and Windows.
    The PowerExchange Logger begins capturing changes based on the new capture registration.
    8If necessary, change the target database definition to reflect the source database metadata changes.
    9In Data Integration, for each mapping that includes the source database, perform the following steps:
    1. aSelect the Source transformation. Under Source Properties, either click the Synchronize button on the Fields tab or select the database again in the Object field on the Source tab. Either action causes the PWX CDC Metadata Adapter to retrieve the updated extraction-map metadata.
    2. bIf you changed the target table, select the Target transformation. Under Target Properties, click the Synchronize button on the Target Fields tab or select the database again in the Object field on the Target tab.
    3. cEdit the field mapping to reflect the added or removed columns.
    10If necessary, rematerialize the target databases.
    11In the mapping task, set a time-based restart point that coincides with the time of target rematerialization or let the mapping task restart from the last checkpoint that was recorded in the state database on the target.
    12Resume change activity on the source database.
    13Start the mapping task again.