Dual-Cluster DR Query Functions

gs_get_local_barrier_status()
Description: If two-city 3DC DR is enabled, the primary cluster and DR cluster synchronize logs. The barrier log is flushed to disks in the primary cluster, and replayed in the DR cluster to determine the archive log progress of the primary cluster and the log replay progress of the DR cluster. gs_get_local_barrier_status is used to query the current log replay status of each node in the DR cluster.

Return type: text

barrier_id: latest barrier ID of a node in the DR cluster.

barrier_lsn: LSN of the latest barrier ID returned by a node in the DR cluster.

archive_lsn: location of archived logs obtained by a node in the DR cluster. This parameter does not take effect currently.

flush_lsn: location of logs that have been flushed to disks on a node in the DR cluster.
gs_hadr_in_recovery()
Description: Checks whether the current node is in barrier-based log restoration if two-city 3DC DR is enabled. If yes, true is returned. Only after the log restoration is complete, can the DR cluster be promoted to the production cluster during the switchover process. This operation must be performed by the system administrator.

Return type: Boolean

This function is used only when a planned switchover is performed in the DR cluster.
gs_streaming_dr_get_switchover_barrier()
Description: Checks whether the CN and first standby DN in the DR cluster have received the switchover barrier logs and replayed the logs in the streaming replication-based two-city 3DC DR solution. If it has, true is returned. In the DR cluster, the procedure for promoting the DR database instance to the production database instance in the switchover process can be started only after the switchover barrier logs of all DNs are replayed (restricted to the system administrator).

Return type: Boolean

Note: This function is used only when a planned switchover is performed in the DR database instance in streaming DR solutions.
gs_streaming_dr_service_truncation_check()
Description: Checks whether the CN and primary DN in the primary cluster has sent the switchover barrier logs in the streaming replication-based two-city 3DC DR solution. If it has, true is returned. The procedure for demoting the production database instance to the DR database instance in the switchover process can be started only after the logs are sent (restricted to the system administrator).

Return type: Boolean

Note: This function is used only when a planned switchover is performed in the DR database instance.

gs_hadr_local_rto_and_rpo_stat()

Description: Displays the log flow control information of the local database instance and DR database instance for streaming DR. (If this command is executed on a node that does not participate in streaming DR, for example, a standby DN or a CN, no information may be returned.)

The return value type is record. The types and meanings of the columns are as described in Table 1.

**Table 1** Parameters of gs_hadr_local_rto_and_rpo_stat
Parameter	Type	Description
hadr_sender_node_name	text	Node name, including the primary database instance and the first standby node of the standby database instance.
hadr_receiver_node_name	text	Name of the first standby node of the standby database instance.
source_ip	text	IP address of the primary DN of the primary database instance.
source_port	int	Communication port of the primary DN of the primary database instance.
dest_ip	text	IP address of the first standby DN of the standby database instance.
dest_port	int	Communication port of the first standby DN of the standby database instance.
current_rto	int	Flow control information, that is, log RTO time of the current primary and standby database instances (unit: second).
target_rto	int	Flow control information, that is, RTO time between the target primary and standby database instances (unit: second).
current_rpo	int	Flow control information, that is, log RPO time of the current primary and standby database instances (unit: second).
target_rpo	int	Flow control information, that is, RPO time between the target primary and standby database instances (unit: second).
rto_sleep_time	int	RTO flow control information, that is, expected sleep time (unit: μs) required by walsender on the host to reach the specified RTO.
rpo_sleep_time	int	RPO flow control information, that is, the expected sleep time (unit: μs) required by xlogInsert on the host to reach the specified RPO.

gs_hadr_remote_rto_and_rpo_stat()

Description: Displays the log flow control information of all other shards or CN database instances and DR database instances for streaming DR. (Generally, this command is executed on CNs. If this command is executed on DNs, no information may be returned.)

The return value type is record. The types and meanings of the columns are as described in Table 2.

**Table 2** gs_hadr_remote_rto_and_rpo_stat
Parameter	Type	Description
hadr_sender_node_name	text	Node name, including the primary database instance and the first standby node of the standby database instance.
hadr_receiver_node_name	text	Name of the first standby node of the standby database instance.
source_ip	text	IP address of the primary DN of the primary database instance.
source_port	int	Communication port of the primary DN of the primary database instance.
dest_ip	text	IP address of the first standby DN of the standby database instance.
dest_port	int	Communication port of the first standby DN of the standby database instance.
current_rto	int	Flow control information, that is, log RTO time of the current primary and standby database instances (unit: second).
target_rto	int	Flow control information, that is, RTO time between the target primary and standby database instances (unit: second).
current_rpo	int	Flow control information, that is, log RPO time of the current primary and standby database instances (unit: second).
target_rpo	int	Flow control information, that is, RPO time between the target primary and standby database instances (unit: second).
rto_sleep_time	int	RTO flow control information, that is, expected sleep time (unit: μs) required by walsender on the host to reach the specified RTO.
rpo_sleep_time	int	RPO flow control information, that is, the expected sleep time (unit: μs) required by xlogInsert on the host to reach the specified RPO.