Database Reference
In-Depth Information
databases store everything in rows and columns. Although they may
support large binary object (LOB) fields that can hold anything, an
object database can support any type of data combined with the pro-
cessing to display it.
Databases
Databases organize data and information into physical structures, which
are then accessed and updated through the services of a database man-
agement system. A database is an organization method that links files
together as required. In nonrelational systems (e.g., hierarchical, network,
etc.), records in one file contain embedded pointers to the locations of
records in another, such as customers to orders and vendors to purchases.
These are fixed links set up ahead of time to speed up daily processing. An
RDBMS is software designed to manage a collection of data, where data is
organized into related sets of tables, rows, and columns so that relation-
ships between and among data can be established. For example, a vehicle
database can contain two tables, one for customer information and one for
vehicle information. An “owns” relationship is then established between
the two tables.
A multidimensional database management system (MDDBMS) is
specifically designed for efficient storage and retrieval of large volumes
of data. Multidimensional databases are organized into fact tables and
dimensions that intersect with the facts table to identify what the fact per-
tains to. Databases of this construction are used for online analytical pro-
cessing, also known as OLAP.
Data Warehouse: Data Marts
A data warehouse is a database designed to support decision making in
an organization or enterprise. It is refreshed, or batch updated, and can
contain massive amounts of data. When the database is organized for one
department or function, it is often called a
data mart
rather than a data
warehouse, as shown in Figure 6.2.
The data in a data warehouse is typically historical and static in nature.
Data marts also contain numerous summary levels. They are structured to
support a variety of elaborate analytical queries on large amounts of data
that can require extensive searching.
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