The data warehouse environment is different. New records can be placed in the data
warehouse. For example, there may be a record of your daily activity. As of July 15, you
had $nnnn dollars in your account. And as of August 3, you had $yyyy dollars in your
account. So, data in the data warehouse are constantly being updated. However, a
historical record is kept in the data warehouse as of the changing values over time.

Fig. 15.1.11 shows that data in the system of record can certainly be updated.

Fig. 15.1.11 Can data inside the system of record be updated?

Detailed and Summary Data in the System of Record

Another important issue is whether the system of record can hold both detailed and
summary data. Of course, the system of record can hold primitive, detailed data. There is
no question about that. But the real question is whether the system of record can hold
summary data.

The answer is yes—of course, the system of record can hold summary data, as seen in
Fig. 15.1.12.

Chapter 15.1: The System of Record