Another variation of the classical ETL interface between the operational environment
and the data warehouse environment is the case where there is a staging area.
Fig. 8.3.4 shows a staging area.
Fig. 8.3.4 Staging area.There are some very specific cases where a staging area is called for. One of those
instances is the case where data from two or more files must be merged and there is a
timing issue. The data from file ABC are ready for merger at 9:00 am, and the data from
file BCD are not ready for a merger until 5:00 pm in the afternoon. In this case, the data
from file ABC must be “staged” until the merge is ready to occur.
A second case for the staging area is where there is a large volume of data and the data
must be separated into different workloads in order to accommodate the parallelization of
the ETL process. In this case, a staging area is needed to separate the volume of data.
Chapter 8.3: The Data Warehouse/Operational Environment Interface