Skip to content
≡

Administrator

Developer

Tools

External Tools

8. ROLE#

The role of replication is used to configure the system to perform special functions by assigning ROLE to replication.

Information about the replication role can be found through the ROLE column value in the V$SYS_REPLICATIONS_ meta table. Replication without a role implies basic 1:1 bidirectional replication between Altibase servers, with a ROLE column value of 0.

There are three types of replication roles: Log Analyzer, Propagable Logging, and Propagation. These roles can be specified when creating replication, and each has the following descriptions:

Log Analyzer Role#

To create replication as a Log Analyzer role, use the ANALYSIS keyword. The Log Analyzer role can be used together with the Propagation role. Please refer to the Log Analyzer User's Manual* For detailed information about the replication with Log Analyzer role.


Propagation#

Propagation refers to configuring the system to propagate replication through multiple nodes.

While normal replication marks the transactions performed by the receiver in the logs to prevent retransmission between each other, propagation allows transactions performed by the receiver to be propagated to other nodes. To leave the logs received by the receiver as replicable logs, the Propagable Logging role is required. Sending the replicable logs to other remote servers is performed by the sender in the replication with the Propagation role.

PROPAGABLE LOGGING Role#

Replication with the PROPAGABLE LOGGING role performs propagable logging, which means logging the transactions that the receiver performed for propagating those transactions to other nodes. In other words, Replication with this role allows the sender specified as PROPAGATION role in the future to read the logs and propagate them to other nodes.

PROPAGATION Role#

The sender with the PROPAGATION role reads not only the replication target logs but also the logs generated by propagable logging, and sends them to other nodes.

Cautions on Replication Propagation#

  • It is recommended not to use it with the RECOVERY option.

    As the sender created with the PROPAGATION role propagates all logs propagable, the system design can become complex as it propagates the logs created by receivers with the RECOVERY option.

  • Replication propagation should be configured in one direction only.

  • Users should take care to avoid creating cycles in the propagation direction, as this can create a situation where changes in the logs are infinitely reapplied.

  • A receiver using PROPAGABLE LOGGING leaves additional information such as PK when logging. Therefore, the receiver with PROPAGABLE LOGGING may have lower transaction performance than those without PROPAGABLE LOGGING.