Purpose
v$ob_cluster displays basic information about the current cluster.
Fields
| Field | Type | Nullable? | Description |
|---|---|---|---|
| cluster_id | bigint(20) | NO | The unique ID of the cluster. |
| cluster_name | varchar(4096) | NO | The name of the cluster. |
| created | timestamp(6) | NO | The time when the cluster was created. |
| cluster_role | varchar(4096) | NO | The role of the tenant in the cluster. Valid values: PRIMARY: indicates the primary cluster.PHYSICAL STANDBY: indicates a standby cluster. |
| cluster_status | varchar(4096) | NO | The state of the cluster. Valid values: VALID: indicates that the cluster is valid.DISABLED: indicates that data synchronization is disabled for the cluster.DISABLED WITH READ ONLY: indicates that the primary cluster is started in read-only mode. The default value is VALID. You can disable the synchronization for a standby cluster in the primary cluster. During a failover, the new primary cluster automatically sets the states of other standby clusters to DISABLED, which means that data synchronization between the primary cluster and standby clusters is disabled. |
| switchover# | bigint(20) | NO | The unique ID of a switchover or failover operation. |
| switchover_status | varchar(4096) | NO | The switchover status of the cluster. Valid values: NOT ALLOWED:NOT ALLOWED, it indicates that the primary cluster cannot be switched to become a standby cluster.NOT ALLOWED, it indicates that the standby cluster cannot be switched to become the primary cluster.TO PRIMARY: Only a standby cluster can have this state. It indicates that the standby cluster can be switched to become the primary cluster.TO STANDBY: Only the primary cluster can have this state. It indicates that the primary cluster can be switched to become a standby cluster.SWITCHOVER SWITCHING: This state indicates that the primary cluster is in the process of being switched to become a standby cluster. A cluster in this state cannot provide write services and internal logging is suspended.FAILOVER FLASHBACK: The standby cluster is in the process of being switched to become the primary cluster and data flashback is being performed to ensure consistency between the clusters. A cluster in this state cannot provide write services. You can keep running the failover command until the standby cluster becomes the primary cluster.FAILOVER CLEANUP: The standby cluster is in the process of being switched to become the primary cluster and the cluster is performing final cleanup jobs, such as deleting invalid freeze information and schemas. A cluster in this state can provide write services but is unsuitable for DDL operations.DISCONNECT: The standby cluster is in the process of decoupling. For example, the cluster name is being changed, or the standby cluster is being unbound from the original primary cluster. A cluster in this state cannot provide write services. You can keep running the decoupling command until the standby cluster is decoupled. |
| switchover_info | varchar(4096) | NO | The information related to the switchover of the cluster. The value of this field is related to the value of the SWITCHOVER_STATUS field. NOT ALLOWED: The field provides the reason why switchover is not allowed for the cluster.TO STANDBY: The field lists the standby clusters that can be switched to become the primary cluster.CHECK PRIMARY CLUSTER SERVER STATUS: indicates that you need to check the states of servers in the primary cluster, because some servers may be offline.CHECK STADNBY CLUSTER SERVER STATUS: indicates that you need to check the states of servers in the standby cluster, because some servers may be offline.CHECK PRIMARY CLUSTER REBALANCE TASK STATUS: indicates that you need to check whether load balancing tasks of the primary cluster have completed.CHECK STANDBY CLUSTER REBALANCE TASK STATUS: indicates that you need to check whether load balancing tasks of the standby cluster have completed.CHECK MERGE STATUS: indicates that you need to check whether error codes exist in the compaction status.NONE SYNCED STANDBY CLUSTER: indicates that the primary cluster cannot be switched to become a standby cluster because no standby cluster synchronous with the primary cluster exists.SYNCED STANDBY CLUSTERS: cluster1, cluster2: lists the standby clusters that are synchronous with the primary cluster.CHECK SYS SCHEMA SYNC STATUS: indicates that you need to check whether the synchronization of the schemas under the system tenant of the standby cluster has completed.CHECK USER SCHEMA SYNC STATUS: indicates that you need to check whether the synchronization of the schemas under common tenants of the standby cluster has completed.CHECK FREEZE INFO SYNC STATUS: indicates that you need to check whether the synchronization of the freeze information of the standby cluster has completed.CHECK ENOUG REPLICA: indicates that you need to check whether the number of replicas in the standby cluster is enough.CHECK REDO LOG SYNC STATUS: indicates that you need to check whether the synchronization of the redo logs of the standby cluster has completed.CAN NOT ACCESS CLUSTERS: cluster1, cluster2: lists the standby clusters that cannot be accessed and whose states need to be checked.NO CLUSTER IN SWITCHING: indicates that no cluster is in the SWITCHING state. Therefore, the switchover to primary operation cannot be performed. This value may be displayed for a standby cluster in the NOT ALLOWED state.INNER ERROR: indicates that an internal error has occurred. You need to check the cluster log for troubleshooting. The related keyword in the log is SWITCHOVER_STATUS.PRIMARY CLUSTER NOT IN SYNC MODE: In maximum protection and maximum availability modes, the log transfer mode of the primary cluster must be set to SYNC. After the switchover, the protection mode remains unchanged and the original primary cluster becomes a synchronous standby cluster. You can modify the log transfer mode on the primary cluster to SYNC to resolve the problem.STANDBY CLUSTER NOT IN SYNC MODE: In maximum protection and maximum availability modes, you can only switch a standby cluster in SYNC mode to become the primary cluster. A standby cluster not in SYNC mode cannot be switched to become the primary cluster.PRIMARY CLUSTER HAS REPLICA IN RESTORE: indicates that a switchover is not allowed because some replicas of the primary cluster have not been created. You must delete these replicas before a switchover can be performed.STANDBY CLUSTER HAS REPLICA IN RESTORE: indicates that a switchover is not allowed because some replicas of the standby cluster have not been created. A switchover can be performed only after these replicas are created.PRIMARY CLUSTER DOING BACKUP: indicates that switchover is not allowed for the primary cluster because it is being backed up. This is because backup is no longer supported after it is switched to become a standby cluster. You can stop the backup task.CHECK OTHER PRIMARY CLUSTER: indicates that switchover is not allowed because another primary cluster exists. This is to prevent the situation where two primary clusters exist. |
| current_scn | bigint(20) | NO | The current system change number (SCN) of the cluster. |
| standby_became_primary_scn | bigint(20) | NO | The SCN at which a standby cluster was forcibly switched to become the primary cluster. Notice The value is not affected by a switchover. You can find this value on the primary and all standby clusters that are functioning properly. |
| primary_cluster_id | bigint(20) | YES | Notice The meaning of this field is different from that of Oracle. In Oracle, if a primary cluster was once a standby cluster, this field records the information about the last primary cluster, and if the primary cluster was never once a standby cluster, the value of this field is NULL. |
| protection_mode | varchar(4096) | NO | The protection mode of the cluster. Valid values: MAXIMUM PROTECTIONMAXIMUM AVAILABILITYMAXIMUM PERFORMANCE |
| protection_level | varchar(4096) | NO | The protection mode of the cluster. Valid values: MAXIMUM PROTECTIONMAXIMUM AVAILABILITYRESYNCHRONIZATIONMAXIMUM PERFORMANCE |
| redo_transport_options | varchar(4096) | NO | The transmission mode of redo logs for the current cluster. Valid values: SYNC/ASYNCNET_TIMEOUT |