Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

Index Classification, Views - Database Management - Lecture Slides, Slides of Introduction to Database Management Systems

Index Classification, Indexes Summary, Views, Security, Efficiency, Characteristics of Views, 3 level schema architecture are the main points of this lecture.

Typology: Slides

2011/2012

Uploaded on 11/03/2012

dharmaraaj
dharmaraaj 🇮🇳

4.4

(65)

153 documents

1 / 16

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
Database
Management
System
Lecture - 39
Docsity.com
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe
pff

Partial preview of the text

Download Index Classification, Views - Database Management - Lecture Slides and more Slides Introduction to Database Management Systems in PDF only on Docsity!

Database

Management

System

Lecture - 39

Index Classification

Clustered vs. unclustered :

 If order of data records is the same as order of index data entries, then called clustered index.

Clustered vs.

Unclustered Index

Index entries Dataentries

direct search for (Index File) (Data file) Data Records

data entries entries^ Data

Data Records

CLUSTERED UNCLUSTERED

When to Use Indexes

Useful on large tables

Required on PK

Useful for attributes appearing

in where, order by and group by

clauses

Indexes Summary

Useful tool to speedup the data access

Can be unique or non-unique

Can be implemented through different techniques

Be careful; they involve overhead

Views

Why Views?

Security

 Show the data to a users’ group that is necessary/required for them  Give only necessary authorizations  No concern with rest of the data

Why Views?

Efficiency

 Part of a query that is frequently used (a subquery), define it as a view  The view definition will be stored and will be executed anytime anywhere view is referred Docsity.com

Characteristics of Views

Not exactly the external views of 3-level schema architecture Major Types  Dynamic  Materialized  Partitioned  Simple/complex

Dynamic Views

Data is not stored for the views

Definition is stored in the

schema

Executed every time view is

referred

Database

Management

System

Lecture - 39