T HE JOB OF THE ORACLE DBA

Vendors often describe their “world”—in the case of Oracle, the term “world” seems
to be correct. What started with a relational database management engine has
grown into a number of development tools, networking products, computer aided
software engineering (CASE) tools, and some complete, industry-specific packages
such as Oracle Financials. Part of the challenge faced by Oracle database administrators
(DBAs) is to determine what parts of this Oracle world they must support
and prepare themselves accordingly. And so begins the challenge.
With many complex topics, it is easiest to start with a brief overview that breaks the
subject down into smaller parts and then explore each of these components
individually. Figure 1.1 graphically portrays an overview of the Oracle world and
some of the interfaces to it that are commonly found.
Figure 1.1.
The world of Oracle. Oracle
CASE
Oracle
Development
Tools
Oracle
Database
Management
System
Oracle
Programmatic
Interfaces
Third-Party
Products
Industry
Applications
The Oracle relational database management system (RDBMS) was the initial
product offering and is at the center of most Oracle product installations. This
product is designed to provide the facilities to store and retrieve information in a
variety of formats. The data entrusted to Oracle is stored in a series of data files on
disk drives of the computer that is running the Oracle RDBMS. If the RDBMS were
limited to a set of disk files, it would be similar to dBASE on a PC. To work in large,
multi-user environments, Oracle has had to add a number of items to the RDBMS
architecture to provide needed services. First, to increase speed on these large
systems and ensure consistency of the data, Oracle uses large areas of computer
memory to store data, transactions, and control information. Next, it implements a
series of background processes to perform part of the work of storing and retrieving
information. This also helps to reduce the complexity of each individual process and
increase the speed of processing, especially on computers with multiple CPUs. To
support data integrity, Oracle keeps a separate record of transactions that are made
T HE W ORLD OF ORACLE AND THE DATABASE A DMINISTRATOR 5
THE WORLD OF ORACLE
1
so that the data can be removed or rolled back if a transaction is canceled or the
system crashes. In addition, there are several types of logs that record transactions
made with the purpose of enabling the data stored in the system to be recovered up
to the point of failure even if a disk drive is completely destroyed. Finally, there are
a set of utilities that provide DBAs with an interface to the database engine and
enables them to perform common tasks such as system startup, data backup and
data loading. It can be quite a complex system, but this is the secret of its power. Only
a few DBAs have to be concerned with all the technical details of the product, and
this knowledge can be built up over time.
Oracle’s next major product line is the series of tools that it provides to build
applications that interface with the RDBMS. One of Oracle’s early product directions
was to build a series of fourth-generation language (4GL) and graphical user
interface (GUI) tools to enable users to rapidly build applications that interfaced
with the Oracle RDBMS. Some of you might be wondering what those terms really
mean. Quite simply, Oracle built tools initially that used very high-level (close to the
English language) commands to access the database and build applications—the
4GL tools. The GUI (often pronounced gooey) part of the story started with form- and
report-building tools that used Lotus-like menus and screen painters to build
applications. Now, some purists may contend that this did not constitute a pure
GUI. Well, one of the main themes in this book is not to dwell on theories and
academic debates. For real-world purposes, this definition should be close enough
to the truth, if there is such a thing. Anyway, Oracle has continued with products
that use pure GUI interfaces, such as those found in Microsoft Windows, the
Macintosh operating system, and the Motif environment. In parallel with this, they
developed interfaces (Oracle pre-compilers) that can be used to access an Oracle
database from within a program written in a common programming language, such
as C or COBOL. The key point to understand from this discussion is a product
direction of using a mix of high-level tools and programmatic interfaces to build
applications. Many competing database vendors designed their application development
tools only around traditional programming languages such as C, COBOL,
etc. Others designed their development tools only around the 4GL approach. Oracle
has a tendency to support a wide range of tools, which has probably helped their
market share because each type of development tool is suited to a different type of
development effort.
A third product line that has been around for several years is a set of computer-aided
software engineering (or CASE) tools. These products are designed to enable you to
capture, in a graphical format, a representation of the application that you wish to
build for review and analysis. There are a number of information engineering rules
and analyses that can be applied to the design to make it more sound. If desired, you
can even instruct the computer to generate major pieces of the application automatically.