Database Reference
In-Depth Information
Figure 24-1.
Illustration of a Star Schema for Graduations from a Regional University
Typical Operations:
A typical data warehouse query may scan thousands or millions
of rows of data. For example, a data warehouse query may involve determining the total
sales for all customers in a specific time period. Except for sophisticated queries, a typical
OLTP or operational database operation accesses only a small percentage of records,
relative to the amount stored. For example, an operational query may involve retrieving
the current purchase order for a particular customer, from a table storing hundreds of
thousands of purchase orders.
Figure
24-2
provides a summary of what we have established so far: that a data
warehouse is typically constructed for various operational databases (sources), and
possesses certain characteristics.
