6596787 dbs connolly 2004 slides09 database planning design
TRANSCRIPT
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
1/56
Chapter 9
Database Planning, Design,
and AdministrationTransparencies
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
2/56
22
Chapter 9 - Objectives
x Main components of an information system.
x Main stages of database system development lifecycle.
x Main phases of database design: conceptual, logical, andphysical design.
x Benefits of CASE tools.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
3/56
32
Chapter 9 - Objectives
x How to evaluate and select a DBMS.
x Distinction between data administration and
database administration.
x Purpose and tasks associated with data
administration and database administration.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
4/56
4
Software Depression
x Last few decades have seen proliferationof software applications, many requiringconstant maintenance involving:
correcting faults,
implementing new user requirements,
modifying software to run on new or upgradedplatforms.
x Effort spent on maintenance began to absorbresources at an alarming rate.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
5/56
5
Software Depression
x As a result, many major software projects were
late,
over budget,
unreliable,
difficult to maintain,
performed poorly.
x In late 1960s, led to software crisis, now referto as the software depression.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
6/56
6
Software Depression
x Major reasons for failure of software projectsincludes:
- lack of a complete requirements specification;
- lack of appropriate development methodology;- poor decomposition of design into manageablecomponents.
x
Structured approach to development wasproposed called Information Systems Lifecycle(ISLC).
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
7/56
7
Information System
Resources that enable collection, management,
control, and dissemination of information
throughout an organization.
x Database is fundamental component of IS, and
its development/usage should be viewed from
perspective of the wider requirements of the
organization.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
8/56
8
Database System Development Lifecycle
x Database planning
x System definition
x Requirements collection and analysis
x Database design
x DBMS selection (optional)
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
9/56
9
Database System Development Lifecycle
x Application design
x Prototyping (optional)
x
Implementationx Data conversion and loading
x Testing
x Operational maintenance
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
10/56
10
Stages of the Database System Development
Lifecycle
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
11/56
11
Database Planning
x Management activities that allow stages of
database system development lifecycle to be
realized as efficiently and effectively as
possible.
x Must be integrated with overall IS strategy of
the organization.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
12/56
12
Database Planning Mission Statement
x Mission statement for the database projectdefines major aims of database application.
x
Those driving database project normally definethe mission statement.
x Mission statement helps clarify purpose of thedatabase project and provides clearer pathtowards the efficient and effective creation ofrequired database system.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
13/56
13
Database Planning Mission Objectives
x Once mission statement is defined,missionobjectives are defined.
x
Each objective should identify a particular taskthat the database must support.
x May be accompanied by some additionalinformation that specifies the work to be done,the resources with which to do it, and themoney to pay for it all.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
14/56
14
Database Planning
x Database planning should also include
development of standards that govern:
how data will be collected,
how the format should be specified,
what necessary documentation will be needed,
how design and implementation should proceed.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
15/56
15
System Definition
x Describes scope and boundaries of database
system and the major user views.
x User view defines what is required of adatabase system from perspective of:
a particular job role (such as Manager or
Supervisor) or
enterprise application area (such as
marketing, personnel, or stock control).
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
16/56
16
System Definition
x Database application may have one or more user
views.
x
Identifying user views helps ensure that no majorusers of the database are forgotten when
developing requirements for new system.
x
User views also help in development of complexdatabase system allowing requirements to be
broken down into manageable pieces.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
17/56
17
Representation of a Database System with
Multiple User Views
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
18/56
18
Requirements Collection and Analysis
x Process of collecting and analyzing information
about the part of organization to be supported
by the database system, and using this
information to identify users requirements ofnew system.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
19/56
19
Requirements Collection and Analysis
x Information is gathered for each major user viewincluding:
a description of data used or generated;
details of how data is to be used/generated;
any additional requirements for new databasesystem.
x Information is analyzed to identify requirements to beincluded in new database system. Described in therequirements specification.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
20/56
20
Requirements Collection and Analysis
x Another important activity is deciding how to
manage the requirements for a database
system with multiple user views.
x Three main approaches:
centralized approach;
view integration approach;
combination of both approaches.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
21/56
21
Requirements Collection and Analysis
x Centralized approach
Requirements for each user view are merged
into a single set of requirements.
A data model is created representing all userviews during the database design stage.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
22/56
22
Centralized Approach to Managing
Multiple User Views
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
23/56
23
Requirements Collection and Analysis
x View integration approach
Requirements for each user view remain as
separate lists.
Data models representing each user view arecreated and then merged later during the
database design stage.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
24/56
24
Requirements Collection and Analysis
x Data model representing single user view (or a
subset of all user views) is called a local data
model.
x Each model includes diagrams and
documentation describing requirements for one
or more but not all user views of database.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
25/56
25
Requirements Collection and Analysis
x Local data models are then merged at a later
stage during database design to produce aglobal
data model, which representsalluser views for
the database.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
26/56
26
View Integration Approach to Managing
Multiple User Views
Pearson Education Limited
1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
27/56
27
Database Design
x Process of creating a design for a database that
will support the enterprises mission statement
and mission objectives for the required
database system.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
28/56
28
Database Design
x Main approaches include:
Top-down
Bottom-up
Inside-out
Mixed
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
29/56
29
Database Design
x Main purposes of data modeling include:
to assist in understanding the meaning
(semantics) of the data;
to facilitate communication about theinformation requirements.
x Building data model requires answering
questions about entities, relationships, and
attributes.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
30/56
30
Database Design
x A data model ensures we understand:
- each users perspective of the data;
- nature of the data itself, independent of its
physical representations;
- use of data across user views.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
31/56
31
Criteria to Produce an Optimal Data Model
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
32/56
32
Database Design
x Three phases of database design:
Conceptual database design
Logical database design
Physical database design.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
33/56
33
Conceptual Database Design
x Process of constructing a model of the data
used in an enterprise, independent ofall
physical considerations.
x Data model is built using the information in
users requirements specification.
x Conceptual data model is source ofinformation for logical design phase.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
34/56
34
Logical Database Design
x Process of constructing a model of the data
used in an enterprise based on a specific data
model (e.g. relational), but independent of a
particular DBMS and other physicalconsiderations.
x Conceptual data model is refined and mapped
on to a logical data model.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
35/56
35
Physical Database Design
x Process of producing a description of the
database implementation on secondary storage.
x Describes base relations, file organizations, andindexes used to achieve efficient access to data.
Also describes any associated integrity
constraints and secuirty measures.
x Tailored to a specific DBMS system.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
36/56
36
Three-Level ANSI-SPARC Architecture
and Phases of Database Design
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
37/56
37
DBMS Selection
x Selection of an appropriate DBMS to support thedatabase system.
x Undertaken at any time prior to logical designprovided sufficient information is available
regarding system requirements.x Main steps to selecting a DBMS:
define Terms of Reference of study;
shortlist two or three products;
evaluate products;
recommend selection and produce report.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
38/56
38
DBMS Evaluation Features
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
39/56
39
DBMS Evaluation Features
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
40/56
40
Example - Evaluation of DBMS Product
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
41/56
41
Application Design
x Design of user interface and application
programs that use and process the database.
x
Database design and application design areparallel activities.
x Includes two important activities:
transaction design;
user interface design.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
42/56
42
Application Design - Transactions
x An action, or series of actions, carried out by a
single user or application program, which
accesses or changes content of the database.
x Should define and document the high-level
characteristics of the transactions required.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
43/56
43
Application Design - Transactions
x Important characteristics of transactions:
data to be used by the transaction;
functional characteristics of the transaction;
output of the transaction;importance to the users;
expected rate of usage.
x Three main types of transactions: retrieval,update, and mixed.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
44/56
44
Prototyping
x Building working model of a database system.
x Purpose
to identify features of a system that work well,or are inadequate;
to suggest improvements or even new features;
to clarify the users requirements;
to evaluate feasibility of a particular systemdesign.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
45/56
45
Implementation
x Physical realization of the database and applicationdesigns.
Use DDL to create database schemas and emptydatabase files.
Use DDL to create any specified user views.
Use 3GL or 4GL to create the applicationprograms. This will include the database
transactions implemented using the DML,possibly embedded in a host programminglanguage.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
46/56
46
Data Conversion and Loading
x Transferring any existing data into new databaseand converting any existing applications to run onnew database.
x Only required when new database system isreplacing an old system.
DBMS normally has utility that loads existingfiles into new database.
x May be possible to convert and use applicationprograms from old system for use by new system.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
47/56
47
Testing
x Process of running the database system with intentof finding errors.
x Use carefully planned test strategies and realistic
data.x Testing cannot show absence of faults; it can show
only that software faults are present.
x Demonstrates that database and applicationprograms appearto be working according torequirements.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
48/56
48
Testing
x Should also test usability of system.
x Evaluation conducted against a usability specification.
x Examples of criteria include:
Learnability;
Performance;
Robustness;
Recoverability;
Adaptability.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
49/56
49
Operational Maintenance
x Process of monitoring and maintainingdatabase system following installation.
x Monitoring performance of system.
if performance falls, may require tuning orreorganization of the database.
x Maintaining and upgrading databaseapplication (when required).
x Incorporating new requirements into databaseapplication.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
50/56
50
CASE Tools
x Support provided by CASE toolsinclude:
- data dictionary to store information about
database systems data;
- design tools to support data analysis;
- tools to permit development of corporate
data model, and conceptual and logical data
models;- tools to enable prototyping of applications.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
51/56
51
CASE Tools
x Provide following benefits:
Standards;
Integration;
Support for standard methods;
Consistency;
Automation .
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
52/56
52
CASE Tools and Database System
Development Lifecycle
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
53/56
53
Data Administration and Database
Administration
x The Data Administrator (DA) and Database
Administrator (DBA) are responsible for
managing and controlling the corporate data
and corporate database, respectively.
x DA is more concerned with early stages of
database system development lifecycle and
DBA is more concerned with later stages.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
54/56
54
Data Administration
x Management of data resource including:
database planning,
development and maintenance of standards,
policies and procedures, and conceptual andlogical database design.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
55/56
55
Data Administration
x Management of data resource including:
database planning,
development and maintenance of standards,
policies and procedures, and conceptual andlogical database design.
Pearson Education Limited 1995, 2005
-
8/14/2019 6596787 DBS Connolly 2004 Slides09 Database Planning Design
56/56
56
Database Administration
x Management of physical realization of a
database system including:
physical database design and
implementation, setting security and integrity controls,
monitoring system performance, and
reorganizing the database.