Scan's default readType is PREAD, and there is a readType transform from PREAD to STREAM when a long scan is executed. E.G. I ask for result of 'count table', and now it will return immediately before the RPC get real data because of this transform, so the result returned maybe incorrect. Although, we can explicitly use STREAM instead of PREAD to avoid this transform. I am still confused, how can we judge whether transform is called? How can I trust my result is real when we allow transform occur?