Thank you very much for your advices. But it is part of my diploma thesis (where I evaluate the use of prediction methods for tuning an database system) using regression methods to predict values. I know that there are problems using the hole time serie to forecast something.

My approach is the following:

- monitoring performance metrics of an IT-system

- create a regression model using the last x snapshots (where x is a constant!!!)

- apply this model for the next time value to forecast the next performance value

If I am not wrong, I implicitly use the same idea like your explained window operator. In the meantime, I found another way to set my input parameters by using the database where all my values are saved.

But now, I have another problem: How can I access the predicted value to use it in my java program???

I really hope that someone can explain it to me...