Effect of nologging and unrecoverable

Therefore, if the changes resulting from a direct path load should be captured by a Capture process, the unrecoverable clause should not be used.

If a data or index segment has the SQL nologging parameter set, the full image redo logging is disabled for that segment, and the invalidation redo is generated. Use of the nologging parameter allows a finer degree of control over the objects that are not logged. This operation does affect the Capture process and subsequently the Replication process. When such nologging and unrecoverable operations are performed at the source database, they need to be repeated at the destination database in order to maintain data synchronization.

Supplemental Logging

The process of logging extra columns of information to the redo log files is called Supplemental Logging. It is not a default behavior. It has to be enabled either at the database level or at the object level. When Supplemental Logging is enabled, selected columns or all columns are specified for extra logging. They are called a supplemental log group, which is nothing but a set of additional columns that are being logged.

Supplemental Logging is necessary for certain columns at a source database in order for changes to those columns to be applied successfully at a destination database. With the help of the values from these additional columns, Oracle decides the rows which need to be updated on the destination side. In this way, supplemental logging is a crucial requirement in most data replication situations.