DDBS 1

Question 1

Distributed Computing:

Answer 1

A number of autonomus processing elements (not necessarily homegeneous) that are interconection by a computer network and that cooperate in performing their assigned task

Question 2

What is being distributed?

Answer 2

Function, Data and Control

Question 3

Distributed function:

Answer 3

Various function of a computer system could be delegated to various pieces of hardware or software

Question 4

Distributed data:

Answer 4

Data used by number of applications may be distributed to a number of processing sites.

Question 5

Distributed control:

Answer 5

The control of the execution of various tasks might be distributed instead of being perfomed by one computer system

Question 6

Why do we ditributed all?

Answer 6

Distributed processing better understads to the organization structure of today’s

Question 7

What applications of computer technology are inherent to distributed architectures?

Answer 7

-Web aplicactions
-Electronic commerce business
-Multimedia applications
-Manufacturing control systems
-Cloud Computing

Question 8

Distributed database(DDB):

Answer 8

is a collection of multiple, logically interrelated database distributed over a computer network

Question 9

Distributed database management system (D-DBMS)

Answer 9

is the software that manages the DDB and provides an access mechanism that makes this distribution transparents to the users

Question 10

Distributed database system(DDBS):

Answer 10

DDBS= DDB + D-DBMS

Question 11

whats is not a DDBS

Answer 11

-Is not a “Colection of files” individually stored at each node of a computer network
-Only physical distribution
-A timesharing computer system
-A loosely or tightly coupled multiprocessor system

Question 12

Data Delivery

Answer 12

Is related to how data is delivery from sites where they are stored to where the query is posed

Question 13

Ther are three ortogonal dimensions into data delivery alteratives(DDA)

Answer 13

-Delivery modes
-Delivery frequency
-Communication methods

Question 14

Delivery modes:

Answer 14

Pull-only and Push-only

Question 15

Pull-only:

Answer 15

The transfer of data from servers to clients is initiated by a client pull.

Question 16

Push-Only:

Answer 16

the transfered of the data from servers to client is initiated by a server push in the absence of any specific request from clients

Question 17

Hybrid

Answer 17

The hybrid mode combines the client-pull and server-push mechanisms

Question 17

Fecuency periodic:

Answer 17

In periodic delivery data are sent from the server to clients at regular intervals

Question 17

Frequency Ad-hoc or irregular:

Answer 17

This delivery is performed mostly in a pure pull-based system

Question 17

Fequency conditional:

Answer 17

In this delivery, data are sent from servers whenever certain conditions installed by clients in their profiles are satisfied

Question 18

Communication methods unicast:

Answer 18

In this method, the communication is performed from a server to a client in a one-to-one fashion

Question 19

Communicaction methods One-to-many

Answer 19

In this method, as the name implies, the server sends data to a number of clients

Question 20

Ditributed DBMS promises

Answer 20

1.- Transparent management of distributed, fragmeted, and replicanted data
2.- Improved reliavility / availability
3.- Improved performance
4.- Easier and more economical system expansion

Question 21

Data independece

Answer 21

Is a fundamental form of transparency that we look for within a DBMS.

Question 22

Network transparency (or distribution transparency)

Answer 22

This is concerned with the user protection from the operational details of the network.

Question 23

Location transparency:

Answer 23

This refers to the fact that command used to perform a task is independent of both location of the data

Question 24

Naming transparency:

Answer 24

This means that a unique name is provided for each object in the database.

Question 25

Replication transparency:

Answer 25

For performance, reliability, and availability reasons, it is usually desirable to be able to distribute data in a replicated fashion across machines on a network

Question 26

Fragmentation transparency:

Answer 26

Sometimes, it is commonly desirable to divide each database relation into smaller fragments and treat each fragment as a separate database object

Question 27

Distributed concurrency control protocols:

Answer 27

They are protocols that control simultaneous transactions in distributed databases

Question 28

Commit protocols:

Answer 28

Protocols that are capable of perform commits operations and recovery unfinished transactions

Question 29

Inter-query parallelism:

Answer 29

This results from the ability to execute multiple queries at the same time

Question 30

Intra-query parallelism:

Answer 30

This is achieved by breaking up a single query into several subqueries each of which is executed at a different site

Question 31

First Normal Form (1NF)

Answer 31

Eliminate the partial functional dependencies of non-prime attributes to key attributes

Question 32

Second Normal Form (2NF)

Answer 32

Eliminate the transitive functional dependencies of non-prime attributes to key attributes

Question 33

Third normal form(3NF)

Answer 33

Eliminate the partial and transitive functinal dependencies of prime (key) attributes to key

Question 34

Outer-Join

Answer 34

Inner join requires the joined tuples from two operand relations to satisfy the join predicate.

Question 35

The semijoin

Answer 35

the semijoin of relation R, defined over the set of attributes A, by relations S, defined over the set of attributes B, is the subset of tumples of R that participate in the join of R with S

Question 36

Computer Network

Answer 36

An interconected collection of autonomous computes that are capable of exchanging information among themselves

Question 37

Computer Network Components

Answer 37

Host (node, end systems) Switches communication link