Retain enough log data on the source system so that Extract can start again from its checkpoints after you stop it or there is an unplanned outage. Extract must have access to the log that contains the start of the oldest uncommitted unit of work, and all logs thereafter. To determine where the Extract checkpoints are, use the INFO EXTRACT command. For more information about INFO EXTRACT, see Reference for Oracle GoldenGate for Windows and UNIX .

If data that Extract needs during processing is not retained, either in online or backup logs, one of the following corrective actions might be required:

• You might need to alter Extract to capture from a later point in time for which log data is available (and accept possible data loss on the target).

• You might need to resynchronize the source and target tables, and then start the Oracle GoldenGate environment over again.

Make certain not to use backup or archive options that cause old archive files to be overwritten by new backups on the source system. New backups should be separate files with different names from older ones. This ensures that if Extract looks for a particular log, it will still exist, and it also ensures that the data is available in case it is needed for a support case.