Database Reference
In-Depth Information
OPERATIONAL
INFORMATIONAL
Data Content
Current values
Archived, derived,
summarized
Optimized for complex
queries
Medium to low
Read
Ad hoc, random, heuristic
Several seconds to minutes
Relatively small number
Data Structure
Optimized for
transactions
High
Read, update, delete
Predictable, repetitive
Sub-seconds
Large number
Access Frequency
Access Type
Usage
Response Time
Users
Figure 20-10
Operational and informational systems.
Such operational applications keep businesses alive. However, executives, man-
agers, and analysts need a different type of informational applications providing
information in different formats, to review past performance, spot future trends, and
make strategic decisions. Whereas operational systems enable you to make the
wheels of business turn, informational systems enable you to watch the wheels
of business turn. Informational systems are decision-support applications.
Figure 20-10 contrasts the features of operational and informational systems.
Decision-support systems provide business intelligence to decision makers. Data
warehousing, online analytical processing (OLAP), and data mining are major deci-
sion-support applications. Database systems for decision support must provide fast
processing of queries, must enable sophisticated analysis along many business
dimensions, and must be able to process large volumes of data.
We will broadly discuss these decision-support systems and consider their pur-
poses, features, and functions. Specifically, we will examine the types of database
systems that are needed for these applications. You will note how these database
systems differ from those for operational systems. You will also observe how deci-
sion-support database systems are designed for analysis whereas operational data-
base systems are geared for performance.
Data Warehousing
Data warehousing is a new system environment that provides strategic information
for analysis and decision making. Organizations that are building data warehouses
are actually building this new system environment. This new environment is kept
separate from the system environment supporting day-to-day operations. A data
warehouse essentially holds the business intelligence for an organization to aid its
strategic decision making. Figure 20-11 shows the nature and composition of busi-
ness intelligence provided by the data warehouse environment.
At a high level of interpretation, a data warehouse contains critical measure-
ments of the business processes stored along business dimensions. For example, a
data warehouse might contain units of sales, by product, by day, by customer group,
by sales district, by sales region, and by promotion. Here the business dimensions
are product, day, customer group, sales district, sales region, and promotion.
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