Answer: 1. Create migration job using Database Migration Service. 2. Set the migration job type to Continuous, and allow the databases to complete the full dump phase and start sending data in change data capture (CDC) mode. 3. Wait for the replication delay to minimize, initiate a promotion of the new Cloud SQL instance, and wait for the migration job to complete. 4. Update your application connections to the new instance.

To minimize downtime for migrating a highly transactional application with a 500 GB MySQL database instance to Cloud SQL, the best approach involves using the Database Migration Service with a Continuous migration job type. This method allows for the initial full dump of the databases followed by continuous replication of changes (CDC mode), ensuring minimal downtime. Option B outlines this process correctly, including the steps to wait for the replication delay to minimize before promoting the new Cloud SQL instance and updating application connections. Option A suggests using Datastream, which is not the most efficient method for minimizing downtime in this scenario. Option C proposes a One-time migration job, which would require a maintenance window and stopping write workloads, leading to more downtime. Option D involves manual steps with mysqldump, which is not scalable or efficient for a 500 GB instance and would result in significant downtime.

Author: LeetQuiz Editorial Team