Course: IKI81404T : Perancangan Sistem Informasi

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PERANCANGAN SISTEM INFORMASI

Session 8 Data Storage Design

Based on System Analysis & Design 2

nd

_Edition

Authors : Alan Dennis & Barbara Haley Wixom

Publisher : John Wiley & Sons

Session 8 Data Storage Design

Based on System Analysis & Design 2

nd

_Edition

Authors : Alan Dennis & Barbara Haley Wixom

(2)

2

Pow erPoint Course Mat er ial for SCELE Graduat e Program I nform at ion Technology

Fa cu lt y of Com put e r Scie n ce – Unive r sit y of I n don e sia

Objectives

Become familiar with several file and database

formats

Understand several goals of data storage

Be able to optimize a relational database for

data storage and data access

Become familiar with indexes

(3)

Key Definitions

The

data storage function

manages how data is

stored and handled by programs that run the

system

Goals of data storage design

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4

(5)

Types of Data Storage Formats

Files:

electronic lists of data optimized to

perform a particular transaction

Database:

a collection of groupings of

information the relate to each other in some

way.

A

Database Management System (DBMS)

is

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Appointment File

(7)

Appointment Database

(8)

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File Attributes

Files contain information formatted for a

particular transaction

Typically organized sequentially

Pointers used to associate records with other

records

(9)

File Types

Master files

store core, important information

Look-up files

store static values

Transaction files

store information that updates a master file

Audit files

record before and after versions of data

History (archive) files

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Database Types

Legacy database

Hierarchical (depict parent-child relationships using

inverted trees)

Network (depict nonhierarchical associations using

pointers)

Relational database

Object database

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Hierarchical Database Example

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Network Database Example

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Relational Database Concepts

Popular; easy for developers to use

Primary

and

foreign keys

used to identify and

link tables

Referential integrity

ensures correct and valid

table synchronization

Structured Query Language (

SQL

)- standard

(14)

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Relational Database Example

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Object Database Concepts

Built around

objects

consisting of both data

and processes

Objects are

encapsulated

(self-contained)

Object

classes

– major object categories

OODBMS

– used primarily for applications with

multimedia or complex data

Hybrid OODBMS

– both object and relational

(16)

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Object Database Example

(17)

Multidimensional Database Concepts

Stores data for easy aggregation and

manipulation across many dimensions

Used for data warehouses and data marts

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Multidimensional Database Example

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Dimensions of Data Storage Optimization

Conflicting goals:

Storage efficiency

(minimizing storage space)

Speed of access

(minimizing time to retrieve

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Storage Efficiency

Minimize null values and redundancy

Reduce update anomalies

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Optimizing Data Storage Efficiency

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Normalization Steps

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Optimizing Access Speed

Techniques available to increase access speed

after optimizing for efficiency

Denormalization

Clustering

• Intrafile

• Interfile

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Denormalization

Add redundancy back to data storage design to

reduce the number of joins performed in a

query

Ideal for frequently queried but rarely updated

data

Look-up tables

1:1 relationships

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Clustering

Reduce the number of times storage must be

accessed by physically placing like records

close together.

Intrafile clustering

– similar records in a table are

stored together

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Indexing

A minitable that contains values from one or

more fields in a table and the location of the

values within the table

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Payment Type Index

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Guidelines for Creating Indexes

Use indexes sparingly for transaction systems

Use many indexes to increase response times in

decision support systems

For each table

Create a unique index based on the primary key

Create an index based on the foreign key

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Volumetrics – Estimating Data Storage Size

Raw data – sum of the average widths of all

fields in a table.

Calculate overhead requirements based on

DBMS vendor recommendations

(31)

Data Storage Size Estimator

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