Schedule Update - Refresh Frequency

We have a dashboard scheduled to be refreshed every day. Currently, we start loading at 11:30 AM in the morning and unload at 11:15 AM in the next day. This means that there is a downtime of 15 mins. 

  1. Is it necessary to have downtime of data? (By downtime I mean that the report is not scheduled and if any user opens the report at that time he will have to fetch data from DB)
  2. What is the minimum downtime I can ensure?

(2) Answers