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Welcome : To the third learning sequence
“ DB ACTORS “
Present learning: We shall explore the following topics:
- DB limitations.
- DB actors.
- DB Administrator.
Recap : In the previous learning sequence, we discussed the:
- What is DB & DBMS.
- Advantages of DBMS.
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DB limitations
The decision to use a DBMS for company’s information needs
as critical as decision to introduce computer in the first
time.
The commission to DBMS in costly because it represent a
large commitment in term of money and human
resources.
The limitations are:
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DB limitations
1- Complexity :
The DBMS is a complex piece of software, it requires DB experts
both to look after it and also to design and develop the database.
2- Cost :
comprehensive DBMS are expensive to purchase and give rise to
additional overhead when in operation.
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DB limitations
3- Inefficiencies :
By no means a database system is inefficient, but what is meant here
that in large systems, whenever weakness appear even though it is
simple, the maintenance of such weakness will take a considerable
time.
4- Rigidity :
The most current DBMS, where designed to manage a particular type
data
( for example, fixed length record ).
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Database Actors
A primary goal of a database system is to retrieve
information from and store new information in the
database. People who work with a database can be
categorized as database actors ( users ).
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Database Actors
1- Database Administrators:
- authorizing access to the database.
- coordinating and monitoring its use.
- acquiring software and hardware resources as needed
- Schema definition.
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Database Actors
2- Database Designers:
- identifying the data to be stored in the database.
- choosing appropriate structures to represent and store
this data undertaken before the database is actually
implemented and populated with data.
- communicate with all prospective database users.
- develop a view of the database that meets the data and
processing requirements for each group of users
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Database Actors
3- End Users:
Access to the database for querying, updating, and generating reports.
3.1- Casual end users:
- occasionally access the database.
- need different information each time.
- learn only a few facilities that they may use repeatedly.
- use a sophisticated database query language to specify
their requests
- typically middle- or high-level managers or other
occasional browsers
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Database Actors
3.2- Naive or parametric end users:
- constantly querying and updating the database, using
standard types of queries and updates called canned
transactions that have been carefully programmed and
tested.
- need to learn very little about the facilities provided by
the DBMS.
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Database Actors
3.3- Sophisticated end users:
- Engineers, scientists, business analysts, and others
who thoroughly familiarize themselves with the facilities
of the DBMS so as to implement their applications to
meet their complex requirements.
- Try to learn most of the DBMS facilities in order to
achieve their complex requirements.
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Database Actors
3.4- Stand-alone users:
-
Maintain personal databases by using ready-made
program packages that provide easy-to-use menu or
graphics-based interfaces. An example is the user of a
tax package that stores a variety of personal financial
data for tax purposes.
- Typically become very proficient in using a specific
software package.
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Database Actors
4- System Analysts and Application
Programmers:
- Determine the requirements of end users, especially
naive and parametric end users, and develop
specifications for canned transactions that meet these
requirements.
- Application programmers implement these
specifications as programs; then they test, debug,
document, and maintain these canned transactions
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Database Actors
5- Workers behind the Scene:
- Typically do not use the database for their own
purposes.
- DBMS system designers and implementers.
- design and implement the DBMS modules (for
implementing the catalog, query language, interface
processors, data access, concurrency control, recovery,
and security. ) and interfaces as a software package.
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Database Actors
6- Tool developers:
- Tools are optional packages that are often purchased
separately.
- include packages for database design, performance
monitoring, natural language or graphical interfaces,
prototyping, simulation, and test data generation.
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Database Actors
7- Operators and maintenance personnel:
- system administration personnel who are responsible
for the actual running and maintenance of the hardware
and software environment for the database system.
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Database Actors
The Data Base Administrator ( DBA ) is the person (or group of person) responsible for
overall control of the database system. DBA will require a number of utility programs
to help on this job such as:
- Loading Routines ( to create the database ).
- Reorganizing Routines (to rearrange space occupied by deleted data).
- Journaling Routines ( to note each operation against the database, together with
identification of the user performance ).
- Recovery Routines ( to restore the database to an earlier state after hardware
software failure).
- Statistical Analysis Routines ( to assist in monitoring performance ).
- Data Dictionary ( the most important tool used by DBA – it is data about data ).
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Summary : In this learning sequence, we discussed the
following:
- DB limitations.
- DB actors.
- DBA tools.
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END
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