Dual-Cluster Replication Parameters

enable_roach_standby_cluster

Parameter description: Specifies whether the instances of the standby cluster are read-only in dual-cluster mode. Only the SYSADMIN user can access this parameter.

Parameter type: Boolean.

Unit: none

Value range:

• on: The read-only mode is enabled for the standby cluster.
• off: The read-only mode is disabled for the standby cluster. In this case, the standby cluster can be read and written.

Default value: off

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is used for backup and restoration. You are advised not to change the value.

Risks and impacts of improper settings: Changing the value of this parameter may cause unexpected results in the cluster. Retain the default value.

RepOriginId

Parameter description: This is a session-level GUC parameter. In bidirectional logical replication, set it to a non-zero value to avoid infinite data replication.

Parameter type: integer.

Unit: none

Value range: 0 to 2147483647

Default value: 0

Setting method: This is a USERSET parameter. Set it based on method 3 provided in Table 2.

Setting suggestion: In two-way logical replication scenarios, set this parameter to a non-zero value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

auto_csn_barrier

Parameter description: Specifies whether the barrier logging function is enabled for the primary cluster and GTM-lite cluster for streaming DR.

Parameter type: Boolean.

Unit: none

Value range:

• on: enabled.
• off: disabled.

Default value: off

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This function is automatically enabled during the DR process. You are advised not to manually disable this function. To enable the read function of the standby node in the GTM-lite cluster, set this parameter to ON.

Risks and impacts of improper settings: If this function is disabled, the data read consistency between the standby cluster for the DR and the standby node of the GTM-lite cluster will be affected.

stream_cluster_run_mode

Parameter description: Specifies whether a CN or DN belongs to the primary or standby cluster in a dual-cluster streaming DR scenario.

Parameter type: enumerated type.

Unit: none

Value range:

• cluster_primary indicates that the node is in the primary cluster.
• cluster_standby indicates that the node is in the standby cluster.

Default value: cluster_primary

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter specifies the status of a standby cluster for DR. It is used in internal processes and can be read by users. You are advised not to modify this parameter.

Risks and impacts of improper settings: Manual modification will cause standby clusters to be abnormal.

hadr_process_type

Parameter description: Specifies a process ID of a streaming replication-based remote DR solution or intra-city dual-DC HA solution.

Parameter type: enumerated type.

Unit: none

Value range:

• none: There is no process.
• failover indicates that a standby cluster for DR is promoted to primary.
• switchover_promote indicates that a standby cluster is promoted to primary during the cluster switchover.
• switchover_demote indicates that a primary cluster is demoted to a standby cluster during the cluster switchover.
• dorado_failover indicates that a Dorado standby cluster is promoted to primary.
• dorado_switchover_demote indicates that a primary cluster is demoted to a standby cluster during the Dorado cluster switchover.
• dorado_failover_abnormal indicates that a standby cluster is promoted to primary when a shared disk of the Dorado primary cluster is faulty.
• dorado_failover_in_standby_stream indicates that a Dorado standby cluster is upgraded to a Dorado primary cluster (also the remote DR-standby cluster) when the remote cluster in the streaming replication-based remote DR solution is the primary cluster.
• dorado_failover_abnormal_in_standby_stream indicates that the intra-city dual-DC HA solution supports streaming replication-based remote DR. In this solution, the remote cluster is the primary cluster for remote DR and the shared disk of the Dorado primary cluster (also the standby cluster for remote DR) is faulty, the Dorado standby cluster is switched to the Dorado primary cluster (also the remote DR standby cluster).

Default value: none

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter specifies the status of a standby cluster for DR. It is used in internal processes and can be read by users. You are advised not to modify this parameter.

Risks and impacts of improper settings: Manual modification will cause standby clusters to be abnormal.

cluster_name

Parameter description: Specifies the name of the current cluster.

cluster_name cannot be set to "invalid_cluster_uuid".

Parameter type: string.

Unit: none

Value range: valid cluster name.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is used in the DR process. The standby cluster for DR identifies the cluster based on this parameter. You are advised not to modify this parameter.

Risks and impacts of improper settings: The manual modification may cause DR function exceptions.

hadr_primary_cluster_name

Parameter description: Specifies the name of the current primary cluster in the DR. This parameter is used to identify the primary cluster in the remote streaming DR deployment where one primary cluster connects to two standby clusters.

When hadr_primary_cluster_name of the main standby cluster in streaming DR mode is set to "invalid_cluster_uuid", log synchronization with the primary cluster is not started, and the standby cluster is continuously disconnected.

Parameter type: string.

Unit: none

Value range: valid cluster name.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter identifies a standby cluster for DR. It is used in DR processes and can be read by users. You are advised not to modify this parameter.

Risks and impacts of improper settings: The manual modification may cause DR function exceptions.

hadr_standby_cluster_num

Parameter description: Specifies the number of standby clusters for streaming DR.

Parameter type: integer.

Unit: none

Value range: 0 to 2147483647

Default value: 0

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter specifies the status of a standby cluster for DR. It is used in DR processes and can be read by users. You are advised not to modify this parameter.

Risks and impacts of improper settings: The manual modification may cause DR function exceptions.