Today, updates to tables are most common. When a need for
near real-time data exists, warehouses can be loaded nearly continuously using a
trickle feed.
Is Cleanliness Best?
Once the data in the warehouse is ???clean,??? is this version of the true nature of the data
propagated back to the originating OLTP systems? This is an important issue for data
warehouse implementation. In some cases, a ???closed loop??? process is implemented
whereby updates are provided back to the originating systems. In addition to minimizing
some of the cleansing that takes place during future extractions, operational
reports become more accurate.
Another viable option is to avoid cleansing by improving the quality of the data at the
time of its input into the operational system. As noted previously in this chapter, this
is critical if OLTP systems are to be directly accessed for business intelligence. Improving
data quality at the source also enables high-speed loading techniques to be used in
near real-time data warehouses (since transformations can be eliminated).
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