My advice is to display the values averaged over time intervals, and also make it possible to zoom in and display a shorter range averaged over shorter intervals, and to display the raw data (no average) when the time range is short enough.
For example:
- when time range is greater than 1 month, average by days
- when time range is less than 1 month and greater than 1 day, average by hours
- when time range is less than 1 day and greater than 1 hour, average by minutes
- when time range is less than 1 hour, raw data only (no average)
By the way, I'm pretty sure you can tell Oracle to do the averaging in the SQL query as a clause in your SELECT statement. I don't know the syntax.