When high availability is enabled for a stand-alone DB system, the DB system has three instances running in different availability or fault domains (Answer D).

High Availability Configuration : This setup involves creating multiple instances of the DB system across different availability or fault domains to ensure redundancy and minimize the risk of downtime due to hardware or network failures.

Instances : Typically, there are three instances—one primary and two replicas—ensuring that the system can failover seamlessly if one instance goes down.

References:

OCI MySQL High Availability

Two methods to import data into a MySQL DB system using MySQL Shell are:

A. util.importTable() : This utility imports data from a file into a table. D. util.loadDump() : This utility loads a previously dumped database or table into a MySQL DB system.

The command mysqlsh john@10.0.1.122 --auth-method=authentication_oci_client does not require a password because it uses the OCI (Oracle Cloud Infrastructure) client authentication method. This method relies on the correct API key-pair specified in the ~/.oci/config file. This file contains the necessary credentials (user OCID, tenancy OCID, API keys, etc.) to authenticate with the OCI environment without needing a password for each connection.

If you cannot connect directly to the MySQL DB system endpoint from your workstation connected to the Internet, the reason is that MySQL DB system endpoint does not have a public IP address (Answer B).

Private Subnet : The MySQL DB system is provisioned in a private subnet, which means it is not directly accessible from the Internet.

Network Accessibility : To access the DB system, you need to establish a secure connection via a VPN, FastConnect, or SSH tunnel.

References:

Connecting to a MySQL DB System

OCI Networking Documentation

To copy transactions from an on-premises MySQL instance to a DB system, you use inbound replication (Answer B).

Inbound Replication : This feature allows the MySQL DB system to receive and apply changes (transactions) from an external MySQL instance.

Replication Configuration : You need to set up replication between the on-premises MySQL instance and the MySQL DB system by configuring the master (on-premises) and the slave (DB system) appropriately.

References:

MySQL Replication Documentation

OCI MySQL Database Service Documentation

A. You can set a value for any global MySQL variable in a configuration : MySQL HeatWave allows you to configure and set global MySQL variables to optimize performance and customize the environment as needed.

C. You can view custom configuration sets with the OCI CLI oci mysql db-system get command : The OCI CLI provides commands to retrieve details about MySQL DB systems, including custom configurations.

The statements CALL sys.ML_TRAIN(‘ml_data.iris’, ‘class’, NULL, @model); and SELECT @model; are used to create and retrieve a machine learning model in MySQL HeatWave AutoML. The following are true:

The generated model handle is shown in the output (Answer B): After training the model, the handle (identifier) for the model is stored in the @model variable and can be retrieved with the SELECT @model; statement.

The statements create a classification model (Answer C): The ML_TRAIN procedure is used to create a classification model since the target column ( class ) indicates a classification problem.

The target column is class (Answer E): The second argument in the ML_TRAIN call specifies the target column for the machine learning model, which is class in this case.

References:

MySQL HeatWave AutoML Documentation

ML_TRAIN Procedure Documentation

A query may not be offloaded to the HeatWave cluster for execution due to the following reasons:

A. The use_secondary_engine session variable is OFF : This setting controls whether queries should be offloaded to the secondary engine (HeatWave). B. The client is connected to the DB system instead of the HeatWave cluster : For queries to be offloaded, the client must be connected to the HeatWave cluster. E. A required column is excluded from the RAPID secondary engine : If a necessary column is not available in the HeatWave (RAPID) secondary engine, the query cannot be offloaded.

In a high-availability DB system, the placement of primary and secondary instances should ensure redundancy across different availability domains (ADs) and fault domains (FDs) to minimize downtime and data loss. The placement mentioned in option D is not valid because it places the primary and secondary instances in the same availability domain and fault domain, which does not provide high availability.

When changing the storage size of a DB system, you cannot decrease the DB system's storage size (Answer B). This restriction ensures data integrity and prevents potential data loss that could occur if the storage size were reduced.

You can only increase the storage size of the DB system.

The storage increase is done online without shutting down the DB system, allowing for uninterrupted operations.

References:

OCI MySQL DB System Scaling Documentation