Which performance feature is NOT supported by Databricks SQL Serverless?

Manual query optimization is not a performance feature supported by Databricks SQL Serverless. This environment is designed to abstract away the underlying infrastructure and provide users with a serverless experience, allowing for automatic scaling and management of resources.

In contrast, the other features are integral to how Databricks SQL Serverless operates. The Photon Engine, for example, is designed to significantly accelerate query performance by optimizing compute and storage. Intelligent workload management enables the system to efficiently allocate resources based on the current demand and workload patterns, which is essential for maintaining optimal performance in a serverless architecture. Predictive IO further enhances performance by anticipating data access patterns and optimizing input/output operations beforehand, thus speeding up query execution.

By not supporting manual query optimization, Databricks SQL Serverless emphasizes ease of use and automation, allowing users to focus on analyzing data rather than tuning queries manually. This design choice aligns with the goal of providing a simplified experience without the complexities of underlying performance tuning.