There is no number
N where N turns performance unacceptable. It's a number that you'll have to derive
yourself, based on parameters of acceptability that you
have to try yourself.
It's misguided to try to find a magic number.
What you'll have is a curve of performance, probably something like this
Records => response time
100 => effectively instant
1000 => 1 sec
10000 => 3 sec
100000 => 10 sec
1000000 => 5 minutes
Once you derive that curve, you can say "OK, if we want to
keep performance around 10 second response time, we can't
have more than 100000 records, and if we want more than that, we're going to have to go to a bigger/different system."
The other part of it is to define very carefully what that
performance acceptability is.
Is it OK if the user has to wait 1 second to do an update?
10 seconds? A minute? Define those, in writing, and make
sure that you get that approved by anyone who could squawk. There's nothing worse than
having your requirements changed out from under you, when
your boss says "Hey, it's taking too long to update", because
you thought that a 5-second lag was acceptable.
xoxo,
Andy
--
Throw down the gun and tiara and come out of the float!