Asynchronous mode of Change Data Capture (CDC) in Oracle

This mode captures change data after the changes have been committed to the source database by using the database redo log files.There are two methods of capturing change data asynchronously, HotLog and AutoLog.

Hotlog:
Change data is captured from the online redo log file on the source database.There is a single, predefined HotLog change source, HOTLOG_SOURCE, that represents the current redo log files of the source database.Change tables for this mode of Change Data Capture must reside locally in the source database.

AutoLog:
Change data is captured from a set of redo log files managed by log transport services. Log transport services control the automated transfer of redo log files from the source database to the staging database. Change sets are populated automatically as new redo log files arrive. The degree of latency depends on frequency of redo log switches on the source database.