Query log stream upgrade and downgrade information

After you enable the arbitration service for a tenant, you can query log stream upgrade or downgrade information through views.

Query log stream upgrade/downgrade events

The sys tenant can query the DBA_OB_SERVER_EVENT_HISTORY view for upgrade or downgrade events of all log streams.

1. Log in to the sys tenant of the cluster as the root user.

2. Execute the following statements to query whether log stream upgrade or downgrade events have occurred.

   • Query log stream downgrade events

     SELECT * FROM oceanbase.DBA_OB_SERVER_EVENT_HISTORY WHERE event LIKE "%DEGRADE%";
     

     If the query result is empty, no log stream downgrade event has occurred. Otherwise, the query result shows the replica information of downgraded log streams and the reasons for the downgrade.

     Reasons for the downgrade include:

     • CRASHED_OR_BROKEN_NETWORK: Indicates that an OBServer node is down or disconnected, or the observer process was killed or exited abnormally.
     • LOG_DISK_HANG_OR_FULL: Indicates that the log disk is stuck in writing (physical failure) or the tenant log disk space is full.
     • SERVER_STOPPED_OR_ZONE_STOPPED: Indicates that the STOP ZONE or STOP SERVER command was executed.
     • LOG_SYNC_DISABLED: Indicates that the replica log synchronization is lagging behind.
     • LOG_VOTE_DISABLED: Indicates that a rebuild operation was performed on the replica.

   • Query log stream upgrade events

     SELECT * FROM oceanbase.DBA_OB_SERVER_EVENT_HISTORY WHERE event LIKE "%UPGRADE%";
     

     If the query result is empty, no log stream upgrade event has occurred. Otherwise, the query result shows the replica information of upgraded log streams.

Query the log stream upgrade and downgrade result

After a log stream upgrade or downgrade event occurs, the sys tenant or a user tenant can query the GV$OB_LOG_STAT or V$OB_LOG_STAT view for the upgrade or downgrade result of the log stream.

1. Log in to the sys tenant or a user tenant as a tenant administrator.

2. Execute the following statement to view the log stream upgrade or downgrade result.

   • sys tenant

     SELECT * FROM oceanbase.GV$OB_LOG_STAT WHERE tenant_id= xxxx;
     

   • User tenant

     MySQL-compatible mode

     Oracle-compatible mode

     The syntax is as follows:

     SELECT * FROM oceanbase.GV$OB_LOG_STAT WHERE tenant_id= xxxx;
     

     The syntax is as follows:

     SELECT * FROM SYS.GV$OB_LOG_STAT WHERE tenant_id= xxxx;
     

   In the query result, view the DEGRADED_LIST column corresponding to the log stream replica whose role is LEADER. If a log stream downgrade event occurs, the log stream replica downgraded due to an exception is displayed in this column. If a log stream upgrade event occurs, the upgraded replica is removed from this column.

References

For more information about log stream upgrade and downgrade, see the following:

• Arbitration service overview

• Modify the log stream downgrade control time