For a MySQL DB system with five active read replicas and a workload consisting mostly of reads, the fastest query response time is achieved by:

C. Connect to the read replica load balancer to perform read-only operations : The read replica load balancer distributes the read workload across all replicas, optimizing performance and response time.

Data loaded into a MySQL HeatWave cluster:

B. Data is partitioned across cluster nodes for scalability : This allows the system to distribute the workload and handle large datasets efficiently. D. Data is stored in hybrid columnar format to speed up analytic queries : The hybrid columnar format optimizes storage and speeds up query performance, especially for analytic workloads.

When automatic backup retention of a DB system is disabled, deleting the DB system (Answer C) will delete all automatic backups of the DB system.

Automatic Backups : These are backups created automatically by the OCI service to ensure data protection.

Backup Deletion : If automatic backups are disabled and you delete the DB system, all associated automatic backups are also deleted. This operation is irreversible, and you should ensure that necessary backups are taken before deleting the DB system.

References:

OCI MySQL Database Service Backup and Restore

To restore a stand-alone DB system to a high-availability DB system with point-in-time recovery, the following are required:

B. Point-in-time recovery must be enabled before the point in time to which you want to restore : Point-in-time recovery (PITR) must be enabled beforehand to allow restoration to a specific point in time. C. An automatic backup taken before the selected point in time must be available : You need an automatic backup from before the desired restore point. D. A manual backup taken before the selected point in time must be available : Manual backups are also essential to ensure you can restore to the desired point in time.

When a DB system has been successfully deleted, the following operations are allowed:

Restore the DB system from an existing manual backup (Answer C): Even after the DB system is deleted, you can restore it from any existing manual backups. This allows you to recover the data and configuration from a point-in-time backup.

View the API call logs on the Audit page (Answer E): You can view the API call logs related to the deleted DB system on the Audit page. These logs provide a record of actions taken on the DB system, including the deletion event.

References:

OCI Backup and Restore Documentation

OCI Audit Documentation

Automatic DB system version upgrades in OCI are performed to the next release in sequence. This means that the system is upgraded to the next available version rather than skipping to the most recent release, ensuring a stable and tested upgrade path.

To replicate data from an on-premises MySQL server to a MySQL DB system running in Oracle Cloud Infrastructure (OCI), where the DB system is connected to a private subnet of a Virtual Cloud Network (VCN), you need to enable the DB system to communicate with the Internet securely. The correct configuration is to create a NAT gateway in the VCN and configure the DB system subnet to route Internet-bound traffic to the NAT gateway (Answer D).

NAT Gateway : A Network Address Translation (NAT) gateway enables instances in a private subnet to initiate outbound traffic to the Internet, but it prevents the Internet from initiating connections to those instances.

Route Table Configuration : You need to update the route table for the private subnet to direct traffic destined for the Internet to the NAT gateway.

Steps:

Create a NAT gateway in the OCI Console.

Update the route table associated with the private subnet to include a route rule that directs all Internet-bound traffic (0.0.0.0/0) to the NAT gateway.

References:

OCI NAT Gateway Documentation

Configuring Routing for Private Subnets

A. Reduce query latency : By distributing read queries across multiple replicas, the load on the primary instance is reduced, which can decrease query latency. D. Scale read queries : Read replicas allow scaling of read operations by providing additional instances to handle read queries, improving overall performance and throughput.

B. ENGINE=csv SECONDARY_ENGINE=lakehouse ENGINE_ATTRIBUTE=’{"file": [{"region": "us-ashburn-1", "namespace": "mytenant", "bucket": "bucket01", "name": "airport.csv"}] }’ : This table option defines a Lakehouse external table based on a CSV file. It specifies the csv engine for the table and uses the lakehouse as the secondary engine, along with the file's location details in OCI Object Storage.