Loading Architecture
Back in Chapter 2, we identified some key software architectural decisions the DBA must make. Principal among those were how many instances will comprise the data warehouse and will the data warehouse data be loaded in one step or two? In this chapter, we will focus on just the latter issue—loading the data.
When loading data into a data warehouse, there are two options (shown in Figure 6-1):
Option 1— Load the data from the source directly into the data warehouse's query tables.
Option 2— Load the data from the source into a staging area first, then into the query tables.
Figure 6-1. Common Data Warehouse ETL Architectures
We'll refer to these approaches as transform, then load and load, then transform, respectively. We ...
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