When creating a Bastion service to connect to a MySQL DB system, the following are true:
* The Bastion CIDR block allowlist must include the IP address of all valid client machines(Answer C):
This ensures that only the IP addresses specified in the allowlist can access the Bastion service, enhancing security by restricting access to known clients.
* The Bastion subnet must have an ingress rule to allow stateful connections on the MySQL DB system port number(Answer E): This allows the Bastion service to communicate with the MySQL DB system by permitting traffic through the necessary ports.
References:
* OCI Bastion Service Documentation
* Setting Up Bastion with MySQL DB System

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

To prepare data for a new DB system with data import in OCI, you shouldexport the data into an Object Storage bucket with a MySQL Shell dump utility(Answer B). This method allows you to store the data in a scalable and durable object storage service before importing it into the new DB system.
Steps:
* Use MySQL Shell dump utility to export the data.
* Save the export files to an Object Storage bucket in OCI.
* Import the data from the Object Storage bucket into the new DB system.
References:
* MySQL Shell Documentation
* OCI Object Storage Documentation

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.

To offload the second query to the HeatWave cluster for execution, you can use the following methods:
* SET use_secondary_engine=FORCED(Answer A): This forces the use of the HeatWave secondary engine for query execution, regardless of the estimated cost.
* SET secondary_engine_cost_threshold=1000(Answer B): This lowers the cost threshold for queries to be offloaded to the HeatWave cluster, allowing queries with lower estimated costs to be offloaded.
Steps:
* Before running the second query, executeSET use_secondary_engine=FORCED;to force the offloading of queries to HeatWave.
* Alternatively, executeSET secondary_engine_cost_threshold=1000;to adjust the cost threshold, making the second query eligible for offloading.