Users connect to Autonomous Data Warehouse by using one of the following consumer groups: High, Medium, and Low. Which statement is true?

The Autonomous Data Warehouse provides predefined consumer groups (database services) to manage workload priorities. The LOW service is designed for background tasks or reporting queries where execution time is not critical. It allocates the least amount of CPU and I/O resources per query but allows for the highest number of concurrent sessions. To maximize concurrency and minimize resource impact, all SQL statements running in the LOW consumer group are executed serially, meaning their Degree of Parallelism (DoP) is set to 1.

B. High provides highest concurrency and lowest resources, and DoP is 1. This is incorrect. The HIGH service provides the lowest concurrency, the highest resources, and uses parallelism (DoP > 1) for maximum performance.
C. Medium provides intermediate resource and concurrency, and queries run serially. This is incorrect. While the MEDIUM service provides a balance of resources and concurrency, its queries run with a limited degree of parallelism, not serially.
D. High provides highest resource and lowest concurrency, and Degree of Parallelism (DoP) is 1. This is incorrect. The HIGH service correctly has the highest resources and lowest concurrency, but it uses a high Degree of Parallelism, not 1.

1. Oracle Cloud Infrastructure Documentation. (2024). Predefined Database Service Names for Autonomous Data Warehouse. In Using Oracle Autonomous Database on Shared Exadata Infrastructure. Section: "Predefined Database Service Names for Autonomous Data Warehouse".

The documentation states for the LOW service: "The LOW database service provides the lowest level of resources and the highest level of concurrency. SQL statements run serially in this service." This directly supports answer A.

For the HIGH service

it states: "The HIGH database service provides the highest level of resources and the lowest level of concurrency." This refutes options B and D regarding concurrency and DoP.

For the MEDIUM service

it notes: "The number of parallel SQL statements is limited in this service

" confirming it does not run serially

which refutes option C.