DR Query Functions for Dual-Database Instances
- gs_get_global_barrier_status()
Description: If two-city 3DC DR is enabled, logs of the primary database instance and standby database instance for DR 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 standby database instance for DR are determined by replaying the standby database instance for DR. gs_get_global_barrier_status is used to query the latest global barrier that has been archived in OBS for the primary database instance.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 two-city 3DC DR solutions based on OBS are enabled, logs of the primary database instance and multiple standby database instances for DR 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 standby database instances for DR are determined by replaying the standby database instances for DR. gs_get_global_barriers_status is used to query the latest global barrier that has been archived in OBS for the primary database instance.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 two-city 3DC DR is enabled, logs of the primary database instance and standby database instance for DR 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 standby database instance for DR are determined by replaying the standby database instance for DR. gs_get_local_barrier_status is used to query the current log replay status of each node of the standby database instance for DR.
Return type: text
barrier_id: latest barrier ID of a node of the standby database instance for DR.
barrier_lsn: LSN of the latest barrier ID returned by a node in the standby database instance for DR.
archive_lsn: location of archived logs obtained by a node in the standby database instance for DR. This parameter does not take effect currently.
flush_lsn: location of logs that have been flushed to disks on a node in the standby database instance for DR.
- gs_upload_obs_file('slot_name', 'src_file', 'dest_file')
Description: Function used by the primary database instance to upload data to OBS if two-city 3DC 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 standby database instance for DR to download data from OBS to the localhost if two-city 3DC DR is enabled.
Return type: void
slot_name: name of the replication slot created for the database instance for DR.
src_file: location of files to be downloaded from OBS.
dest_file: location of the downloaded file in the data directory of the standby database instance for DR.
- gs_get_obs_file_context('file_name', 'slot_name')
Description: Queries file content on OBS if two-city 3DC 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 database instance or database instance for DR.
- gs_set_obs_file_context('file_name', 'file_context','slot_name')
Description: Creates a file on OBS and writes content into the file if two-city 3DC 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 database instance or database instance for DR.
- gs_get_hadr_key_cn()
Description: Creates a file on OBS and writes content into the file if two-city 3DC 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 database instance or database instance for DR.
- gs_hadr_has_barrier_creator()
Description: Checks whether the barrier_creator thread exists on the current node if two-city 3DC DR is enabled. If the thread exists, true is returned (the SYSADMIN permission is required).
Return type: Boolean
Note: This function is used only when a planned switchover is performed on the standby database instance for DR.
- gs_hadr_in_recovery()
Description: Checks whether the current node is in barrier-based log restoration if two-city 3DC DR is enabled. If the current node is in barrier-based log restoration, true is returned. The standby database instance for DR can be promoted to the production database instance through the switchover process only after the log restoration is complete (the SYSADMIN permission is required).
Return type: Boolean
Note: This function is used only when a planned switchover is performed on the standby database instance for DR.
- gs_streaming_dr_get_switchover_barrier()
Description: Checks whether the DN instance of the standby database instance for DR has received the switchover barrier logs and replayed the logs in two-city 3DC DR solutions based on streaming replication. If it has, true is returned. In the standby database instance for DR, the procedure for promoting the standby database instance for DR 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 system administrators).
Return type: Boolean
Note: This function is used only when a planned switchover is performed on the standby database instance for DR 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 two-city 3DC DR solutions based on streaming replication. If it has, true is returned. The procedure for demoting the production database instance to the standby database instance for DR in the switchover process can be started only after the logs are sent (the SYSADMIN permission is required).
Return type: Boolean
Note: This function is used only when a planned switchover is performed on the standby database instance for DR.
- 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 main standby node of the standby database instance.
hadr_receiver_node_name
text
Name of the main 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 main standby DN of the standby database instance.
dest_port
int
Communication port of the main 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 for inserting Xlogs on the host to reach the specified RPO.
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