Reduction of the `online' calibrations to `offline' calibrations

Let's show that the `offline' model can handle `online' calibrations at the expense of adding a database operation to truncate the open-ended validity intervals.

For example, our `online' calibrations with open-ended validities Figure 1 reproduced below in Figure 5 become `offline' calibrations with closed time intervals as in Figure 6.

  

Figure 5:

  

Figure 6:

What happens? We extended the `offline' model by adding open-ended intervals and when we add a new calibration we truncate the open-ended validity interval of the old calibration.

Suppose we were to add cal₄ at t₄, then Figure 6 becomes Figure 7.

 

Figure 7:

  

Figure 8:

Note that the bad query problem is still with us, but we no longer need to concern ourselves with two types of calibrations because the extended `offline' model handles both types.