2. Database System Concepts and Architecture

Question 1

client module

Answer 1

runs on user workstation or personal computer (handles user interaction and provides user-friendly interfaces)

Question 2

server module

Answer 2

Handles data storage, access, search etc.

Question 3

client/server DBMS architecture

Answer 3

system functionality is distributed between two types of modules

Question 4

data model

Answer 4

a collection of concepts that can be used to describe the structure of a database

Question 5

high-level / conceptual data model

Answer 5

close to user perception of data

Question 6

low-level / physical data model

Answer 6

describe details of how data is stored

Question 7

entity

Answer 7

a real-world object or concept that is described in the database

Question 8

representational / implementation data models

Answer 8

provide concepts that may be understood by end users but that are not too far removed from the way data is organized within the computer

Question 9

attribute

Answer 9

some property of interest that further describes an entity

Question 10

relationship

Answer 10

an association among two or more entities

Question 11

access path

Answer 11

structure that makes the search for particular database records efficient

Question 12

object data models

Answer 12

higher-level implementation data model that are closer to conceptual data models

Question 13

database schema

Answer 13

description of a database (during design, does not change often)

Question 14

schema diagram

Answer 14

displayed schema with schema constructs (no instances)

Question 15

database state or snapshot / current set of occurrences or instances

Answer 15

the data in the database at a particular moment in time

Question 16

valid state

Answer 16

a state that satisfies the structure and constraints specified in the schema

Question 17

meta-data

Answer 17

descriptions of the schema constructs and constraints

Question 18

intension of a database

Answer 18

the database schema

Question 19

extension of schema

Answer 19

database state

Question 20

three-schame architecture (goal)

Answer 20

separate user applications and physical database

Question 21

internal level / internal schema

Answer 21

describes physical structure of database

Question 21

conceptual level / conceptual schema

Answer 21

describes structure of whole database for community of users

Question 22

external or view level

Answer 22

includes number of external schemas or user views

Question 22

mappings

Answer 22

process of transforming requests and results between levels

Question 23

levels of three-schema architecture

Answer 23

1. internal 2. conceptual 3. external

Question 24

operating system (OS)

Answer 24

system that controls access to database disk (with stored data manager module)

Question 25

stored data manager module

Answer 25

carry out low-level data transfer between disk and computer main storage (sometimes buffer handling)

Question 26

buffer manager module

Answer 26

module for handling buffering of disk pages

Question 27

DDL compiler

Answer 27

processes schema definitions and stores meta-data in DBMS catalog

Question 28

Runtime database processor

Answer 28

handles database accesses at runtime (retrieves and carries out retrieval or update operations)

Question 29

Query compiler

Answer 29

handles high-level queries

Question 30

precompiler

Answer 30

extracts DML commands from an application program (in host programming language)

Question 31

DML compiler

Answer 31

compiles DML commands into object code for database access

Question 32

host language compiler

Answer 32

compiles the rest of the program (without DML commands)

Question 33

client/server architecture

Answer 33

deal with environments with large number of PCs, workstations, file servers etc connected via a network

Question 34

specialized servers

Answer 34

e.g. file server, printer server, web server, e-mail server

Question 35

client machines

Answer 35

provide user with appropriate interfaces to utilize these servers

Question 36

client

Answer 36

a user machine that provides user interface capabilities and local processing

Question 37

server

Answer 37

a machine that can provide services to the client machines (file access, printing, archiving, database access)

Question 38

Two-tier architectures

Answer 38

software components are distributed over two systems: client and server

Question 39

advantage two-tier

Answer 39

simplicity and seamless compatibility with existing systems

Question 40

middle tier, application server, Web server

Answer 40

Plays intermediate role by storing business rules that are used to access data from the database server

Question 41

What are the three tiers

Answer 41

user interface, application rules, data access