Why do you have 6 different market watch table ?

We track price changes in 6 different time windows:

a) Today price change: Price changes since today morning until now

b) 1 Day Price change: Price changes since yesterday morning until now

c) 3, 7, 15, 30 days Price changes: Price changes in the last 3, 7, 15, 30 days respectively

How often do you update your market watch table ?

Typically 30 minutes to 2 hours depends on server load.