The downstream mining database topology has been available since Oracle GoldenGate 11g Release 2. Its functionality is reminiscent of Oracle Streams, where both the capture and apply processes are configured on the target system. Known as source database offloading, the source database sends its redo stream to the target system. Here, the Extract process uses the Logminer server on the downstream database to mine the logs.
The configuration is largely conducted on the source and target database to enable the Oracle Data Guard transport mechanism of log shipping. This can be in real-time mode or archive log shipping mode. Configuring the former allows Oracle to fall back to the latter when it is under extreme load or experiencing network latency.
The following diagram illustrates the architecture of the downstream mining database that includes the naming convention used in the example configuration:
