MySQL 8.0 Database Administrator — Question 84

An attempt to recover an InnoDB Cluster fails.
Examine this set of messages and responses:
host3:3377 ssl JS > dba.rebootClusterFromCompleteOutage()
Reconfiguring the default cluster from complete outage…
The instance ‘host1:3377'’ was part of the cluster configuration.
Would you like to rejoin it to the cluster? [y/N]: y
The instance ‘host2:3377’ was part of the cluster configuration.
Would you like to rejoin it to the cluster? [y/N]: y
Dba.rebootClusterFromCompleteOutage: The active session instance isn’t the most updated in comparison with the ONLINE instances of the Cluster’s metadata. Please use the most up to date instance: ‘host1:3377’. (RuntimeError)
Which statement is true?

Answer options

• A. The instance deployed on host3 must be rebuilt with a backup from the primary instance.
• B. The cluster is running and there is at least one ONLINE instance.
• C. The instance deployed on host3 must be synchronized from a donor deployed on host1 by using the command cluster.addInstance(‘host1:3377’).
• D. It is possible to determine the most up-to-date instance by comparing different global transaction identifier (GTID) sets with GTID_SUBSET(set1,set2).
• E. The active session instance is invalid and must be re-created by using the command shell.connect(‘host3:3377’).

Correct answer: C

Explanation

The correct answer is C because the instance on host3 needs to synchronize with the most up-to-date instance on host1 to ensure it has the latest data. Option A is incorrect as rebuilding from a backup is not necessary if synchronization can be performed. Option B is misleading because, although there is at least one ONLINE instance, host3 is not updated. Options D and E do not address the core issue of syncing with the primary instance.