What is the meaning of 'Local Disk IO' in the query profiler?

• A. The time spent on data processing by the CPU.
• B. The time when the processing was blocked by local disk access.
• C. The time when the processing was waiting for the network data transfer.
• D. The time spent on memory allocations.

Answer: (B)

Local Disk IO means the time the query spends waiting on I/O operations to the compute node’s local storage. It reflects moments when processing is blocked because data must be read from or written to the local disk, not because of CPU work or network transfers. So the best description is that the processing was blocked by local disk access. If you see this value high, it points to disk I/O bottlenecks on the warehouse node rather than CPU or memory contention.