What is the default state of parallelism for SELECT queries in Autonomous Data Warehouse?

In Oracle Autonomous Data Warehouse, the default state of parallelism for SELECT queries is enabled. This design decision is made to optimize performance, particularly for analytical workloads that often involve large datasets. Enabling parallelism allows the database to utilize multiple CPU cores to process queries, breaking down the work into smaller tasks that can be executed simultaneously. This can lead to significant reductions in the time it takes to retrieve results for complex queries.

The system automatically manages the degree of parallelism based on various factors such as the available resources and the nature of the query, ensuring that operations are performed efficiently without requiring manual intervention from the user. Given that Autonomous Data Warehouse is designed to streamline operational complexity, having parallelism enabled by default aligns with the goal of maximizing performance while simplifying the user experience.

Considering this default behavior, other options like not enabling parallelism or having it depend on user roles do not reflect the architecture and intent behind the Autonomous Data Warehouse, which is to provide an optimized, automated environment for data analysis. Thus, enabling parallelism by default is crucial for achieving high-performance query execution on large volumes of data.