On Fri, Jan 7, 2011 at 5:21 PM, Oliver Kohll - Mailing Lists
<oliver.lists@gtwm.co.uk> wrote:
Charts are updated once a day overnight, or cached whenever someone looks at them in the system underlying the dashboard, so they are at most one day old. A chart is also updated when a user clicks on it to drill down to the data.
Of course what you decide depends on what the business use case is and what demands there are on the system. In my cases so far the slowest charts take 1 or 2 seconds to generate by SQL so if necessary, each could be loaded in in real time over AJAX, though that hasn't been needed yet.
We found for our use case that customers don't like "1 day old" reports. We've moved much of our dashboard statistics to trigger-based materialized view, so whenever they reload, they get current numbers and the cost to compute those numbers has already been amortized over the metric-gazillion updates and inserts that comprise them. :) Computing them on-the-fly is just too time consuming and people don't like to wait, either.