Before the system can use a summarization level to read data, it needs to be supplied with data. You do this in the application menu by choosing Tools ® Summarization levels ® Update...

The summarization levels are updated at fixed intervals and not by transaction. You can update them at night, when the system workload is otherwise low. The periodic method also makes it possible to make changes to the summarization levels en masse.

Once you have finished defining a summarization level, it retains the status "Active, without data" until you create data for the level. This is referred to as "building" the summarization level. Once you have done this, the status changes to "Active", and you can use the summarization level in the information system, planning and cost center assessment. When you build a summarization level, the system reads the data from the segment level.

In order to keep your summarization levels up to date, you need to update the data on a regular basis. When you do this, the system reads the changes that have been made since you last updated or created the data (so-called "delta method"). The system reads the new line items here. If a large amount of new data exists, it may make more sense to delete the data completely from the summarization level and then create it again.

The delta method relies on a time stamp which is contained in each line item, record in the segment level and summarization level. This time stamp makes it possible for the system to decide which line items are already contained in the summarization level. However, if you are using more than one computer (database/application servers), these could show a slight difference in their system times. The system can correct inaccuracies of up to half an hour by ignoring any postings made in the last half hour.