SOLIX Technologies

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INTRODUCTION
A database administrator in any company is responsible for establishing policies
and procedures pertaining to the management, security, maintenance and use of
database management systems. Besides planning, implementing and
maintaining databases for a company, they also play a key role in training users,
programmers and test engineers on database use and procedures. A Database
administrator's role requires knowledge in the following area:
Different computer platforms and operating systems existing
within an enterprise.
Database component and their interaction with each other.
Varied business rules defining the database system.



ORACLE DATABASE ARCHITECTURE
Overview
The Oracle Database is a repository of storable, updateable, and retrievable
data. The database itself is a collection of physical and logical structures
consisting of system, user, control, and datafiles. The files are collectively known
as the Oracle Database system. The Oracle Database server manages these
files.
2.1 The Database
The databases refer to the physical storage of data. Oracle Database System is
based on the relational database management model. The data is stored in twodimensional
tables composed of columns and rows. The columns of an individual
table define the relational tables. Each of these columns defines a particular type
of data and is called an attribute. The data pertaining to an individual set of
records is stored in the rows. Individual tables can be related to each other.
These tables may even contain object-oriented structures such as abstract data
types and methods. All the data is stored in files and can be retrieved by using
database structures that provide the logical mapping of the data onto the files.
Different data types are stored individually in this manner.



2.2 The Instance
Instances refer to a particular set of software programs executed by the server.
This software provides access to the data stored in the database. The set of
processes that facilitate the storing, updating and retrieving the data along with
the allocated memory on the database server form the Instance of the database.
Instance acts as the interface that allows the users to communicate with the
server. The data flows between a user and the database only if the instance is
operational.