Ordered analytical functions provide support for many common operations in analytical processing and data mining that require an ordered set of results rows or depend on values in a previous row. Ordered analytical functions enable and expedite the processing of queries containing On Line Analytical Processing (OLAP) style decision support requests.
For example, computing a seven-day running sum requires:
- First, that rows be ordered by date.
- Then, that the value for the running sum be computed by:
- Adding the current row value to the value of the sum from the previous row, and
- Subtracting the value from the row eight days ago.