DR Query Functions for Dual-Database Instances
- gs_get_global_barrier_status()
Description: If the 3DC geo-redundant DR is enabled, logs of the primary database instance and DR database instance are synchronized through OBS. The barrier log is flushed to the disk of the primary database instance. The progress of archiving logs of the primary database instance and the progress of replaying logs of the DR database instance are determined by replaying the DR database instance. gs_get_global_barrier_status is used to query the latest global barrier that has been archived in OBS for the primary database instance.
Return type: text
global_barrier_id: globally latest barrier ID.
global_achive_barrier_id: globally latest archived barrier ID.
- gs_get_global_barriers_status()
Description: If 3DC geo-redundant DR solutions based on OBS are enabled, logs of the primary database instance and multiple DR database instances are synchronized through OBS. The barrier log is flushed to the disk of the primary database instance. The progress of archiving logs of the primary database instance and the progress of replaying logs of the DR database instance are determined by replaying the DR database instances. gs_get_global_barriers_status is used to query the latest global barrier that has been archived in OBS for the primary database instance.
Return type: text
slot_name: name of the slot used for DR.
global_barrier_id: globally latest barrier ID.
global_achive_barrier_id: globally latest archived barrier ID.
- gs_get_local_barrier_status()
Description: If 3DC geo-redundant DR is enabled, logs of the primary database instance and DR database instance are synchronized through OBS. The barrier log is flushed to the disk of the primary database instance. The progress of archiving logs of the primary database instance and the progress of replaying logs of the DR database instance are determined by replaying the DR database instance. gs_get_local_barrier_status is used to query the current log replay status of each node of the DR database instance.
Return type: text
barrier_id: latest barrier ID of a node of the DR database instance.
barrier_lsn: LSN of the latest barrier ID returned by a node in the DR database instance.
archive_lsn: location of archived logs obtained by a node in the DR database instance. This parameter does not take effect currently.
flush_lsn: location of logs that have been flushed to disks on a node in the DR database instance.
- gs_upload_obs_file('slot_name', 'src_file', 'dest_file')
Description: Function used by the primary database instance to upload data to OBS if 3DC geo-redundant DR is enabled.
Return type: void
slot_name: name of the replication slot created for the primary database instance.
src_file: location of the file to be uploaded in the data directory of the primary database instance.
dest_file: location of the file to be uploaded to OBS.
- gs_download_obs_file('slot_name', 'src_file', 'dest_file')
Description: Function used by the DR database instance to download data from OBS to the local host if 3DC geo-redundant DR is enabled.
Return type: void
slot_name: name of the replication slot created for the DR database instance.
src_file: location of files to be downloaded from OBS.
dest_file: location of the downloaded file in the data directory of the DR database instance.
- gs_get_obs_file_context('file_name', 'slot_name')
Description: Queries file content on OBS if 3DC geo-redundant DR is enabled.
Return type: text
file_name: name of the file on OBS.
slot_name: name of the replication slot created for the primary or DR database instance.
- gs_set_obs_file_context('file_name', 'file_context','slot_name')
Description: Creates a file on OBS and writes content into the file if 3DC geo-redundant DR is enabled.
Return type: text
file_name: name of the file on OBS.
file_context: content to be written into the file.
slot_name: name of the replication slot created for the primary or DR database instance.
- gs_get_hadr_key_cn()
Description: Creates a file on OBS and writes content into the file if 3DC geo-redundant DR is enabled.
Return type: text
file_name: name of the file on OBS.
file_context: content to be written into the file.
slot_name: name of the replication slot created for the primary or DR database instance
- gs_hadr_has_barrier_creator()
Description: Checks whether the barrier_creator thread exists on the current node if 3DC geo-redundant DR is enabled. If yes, true is returned (restricted to the system administrator).
Return type: Boolean
Note: This function is used only when a planned switchover is performed on the DR database instance.
- gs_hadr_in_recovery()
Description: Checks whether the current node is in barrier-based log restoration if 3DC geo-redundant DR is enabled. If yes, true is returned. The DR database instance can be promoted to the production database instance through the switchover process only after the log restoration is complete (restricted to the system administrator).
Return type: Boolean
Note: This function is used only when a planned switchover is performed on the DR database instance.
- gs_streaming_dr_get_switchover_barrier()
Description: Checks whether the DN instance of the DR database instance has received the switchover barrier logs and replayed the logs in 3DC geo-redundant DR solutions based on streaming replication. If it has, true is returned. In the DR database instance, 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 DN instances are replayed (restricted to the system administrator).
Return type: Boolean
Note: This function is used only when a planned switchover is performed on the DR database instance in streaming DR solutions.
- gs_streaming_dr_service_truncation_check()
Description: Checks whether the DN instance of the primary database instance has sent the switchover barrier logs in 3DC geo-redundant DR solutions based on streaming replication. 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 on the DR database instance.
- gs_hadr_local_rto_and_rpo_stat()
Description: Displays the log flow control information about the primary and standby database instances in the streaming DR scenario. (This view can be used only on the primary DN of the primary database instance. Statistics cannot be obtained from the standby DN or the standby database instance.)
Return type: record. The types and meanings of the fields are as follows:
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, the 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, the RPO time between the target primary and standby database instances (unit: second).
rto_sleep_time
int
RTO flow control information, that is, the 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 the primary and standby database instances of other non-local data shards in streaming DR mode. This function is not supported in centralized deployment scenarios.
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