During data loads, by default, Essbase overwrites database values with data-source values. However, you can subtract data-source values from database values. For example, to track available budget by week, you can subtract weekly data expenditures from previous week budget values.
If the subtraction option is used and committed transactions are not used and a failure occurs, recovery may be difficult.
To subtract from data values:“Adding to and Subtracting From Existing Values” in the Oracle Essbase Database Administrator's Guide
import data (aggregate storage) (MaxL) in the Oracle Essbase Technical Reference