An analytics team supports a dashboard that is queried in short bursts during the working day and sits idle for hours in between. They are comparing a serverless SQL warehouse with a classic SQL warehouse. Which statement correctly describes the difference between the two?
- AA classic warehouse resumes in a few seconds because its virtual machines are held ready in the customer's cloud account, whereas a serverless warehouse has to acquire capacity for each query it receives.
- BA serverless warehouse draws on compute managed in the Databricks account and becomes available within seconds, whereas a classic warehouse provisions virtual machines in the customer's cloud account and takes minutes. Correct
- CA serverless warehouse accepts read queries alone, so any statement that writes to a Unity Catalog table has to be routed to a classic warehouse running in the same workspace.
- DThe two run on identical infrastructure and differ only in how the charge is presented on the bill, so the start-up time and the location of the compute are the same for both.
Why A is wrong: This inverts the two, which is a common mix-up; classic warehouses are the ones that must provision virtual machines on resume, and serverless warehouses do not acquire capacity separately for each query.
Why B is correct: Serverless SQL warehouses use capacity that Databricks manages and keeps ready, so a start or resume completes in seconds, while a classic warehouse must launch virtual machines in the customer's cloud subscription first.
Why C is wrong: It sounds like a reasonable restriction on managed compute, but serverless SQL warehouses run the same SQL surface as classic ones, including writes such as MERGE and INSERT.
Why D is wrong: Billing does differ, but that is a consequence rather than the distinction; the compute genuinely runs in different places and becomes available on very different timescales.