Understanding change management

CDC Replication maintains and depends on metadata describing source and target tables and columns being replicated. When Data Definition Language (DDL) changes occur that result in changes to the source or target table structures, CDC Replication will no longer have the correct information with which to read source database log records to capture change data during mirroring.

For that reason, following a DDL change that results in table structural changes, CDC Replication requires some action to update its metadata before replication can be performed or resumed.

As long as there is no Data Manipulation Language (DML) activity following a DDL statement that affects replication, it is possible to resume mirroring once some specific actions have been taken. If there is DML for the affected table following a DDL operation, a full refresh may be required for the table which has been changed.

In a best case scenario, a DDL change that will affect replication should be known and planned in advance.