Google Cloud Professional Cloud Database Engineer — Question 124

You are managing a Cloud SQL for PostgreSQL instance in Google Cloud. You have a primary instance in region 1 and a read replica in region 2. After a failure of region 1, you need to make the Cloud SQL instance available again. You want to minimize data loss and follow Google-recommended practices. What should you do?

Answer options

• A. Restore the Cloud SQL instance from the automatic backups in region 3.
• B. Restore the Cloud SQL instance from the automatic backups in another zone in region 1.
• C. Check "Lag Bytes" in the monitoring dashboard for the primary instance in the read replica instance. Check the replication status using pg_catalog.pg_last_wal_receive_lsn(). Then, fail over to region 2 by promoting the read replica instance.
• D. Check your instance operational log for the automatic failover status. Look for time, type, and status of the operations. If the failover operation is successful, no action is necessary. Otherwise, manually perform gcloud sql instances failover.

Correct answer: C

Explanation

The correct answer is C because it involves checking the replication lag and promoting the read replica, which minimizes data loss. Options A and B involve restoring backups, which could lead to greater data loss if the primary instance was more recent. Option D may not be effective if the failover was unsuccessful, as it does not ensure the availability of the instance immediately.