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Database Management Fall 2003 Data Processing Architecture Chapter 12. Personal database. Local storage and processing Advantages Personal computers are cheap Greater control Friendlier interface Disadvantages Replication of applications and data Difficult to share data

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slide1

Database Management

Fall 2003

Data Processing

Architecture

Chapter 12

personal database
Personal database
  • Local storage and processing
  • Advantages
    • Personal computers are cheap
    • Greater control
    • Friendlier interface
  • Disadvantages
    • Replication of applications and data
    • Difficult to share data
    • Security and integrity are lower
    • Disposable systems
    • Misdirection of attention and resources
host terminal
Host/terminal
  • Remote storage and processing
  • Associated with mainframe computers
  • All shared resources are managed by the host
  • Upgrades are in large chunks
lan architectures
LAN architectures
  • A LAN connects computers within a geographic area
  • Transfer speeds of up to 1,000 Mbits/sec
  • Permits sharing of devices
  • A server is a computer that provides and controls access to a shareable resource
client server 2nd generation
Client/Server - 2nd Generation
  • Two-tier solution
  • Client runs application, Server provides resources

DC

Application

Client

manager

Operating system

DC

DBMS

DC

Application

manager

Client

manager

LAN

Operating system

Operating system

Server

DC

Application

manager

Client

Operating system

client server
Client/Server
  • Client is typically a PC or workstation
  • Server is typically a larger with multiple cpu and gigabytes of memory and disk space
client server 2nd generation8
Client/Server - 2nd Generation
  • Three-tier solution – best of both worlds
  • Client runs thin client, Server provides resources, App Server runs application

DC

Thin client

manager

Operating system

DC

Application

DC

Browser

DC

DBMS

manager

manager

manager

LAN

Operating system

Operating system

Operating system

Application server

Data server

Browser

DC

manager

Middleware

Operating system

client server9
Client/server
  • Client is typically a PC and browser
  • Application server is typically a web server
n tier architecture
N-tier Architecture

Database

Server

Application

Server

Database

Application

Server

Web

Server

Firewall

Database

Server

Client

Database

Internet

Client

distributed database
Distributed database
  • Communication charges are a key factor in total processing cost
  • Transmission costs increase with distance
    • Local processing saves money
  • A database can be distributed to reduce communication costs
distributed database14
Distributed database
  • Database is physically distributed as semi-independent databases
  • There are communication links between each of the databases
  • Appears as one database
distributed database15
Distributed Database

homogeneous distributed database

a hybrid
A hybrid
  • Architecture evolves
    • Old structures cannot be abandoned
    • New technologies offer new opportunities
  • Ideally, the many structures are patched together to provide a seamless view of organizational databases
  • Distributed database principles apply to this hybrid architecture
distributed database17
Distributed Database

Homogeneous

Envirnoment

Heterogeneous

Envirnoment

distributed database access
Distributed database access
  • Remote Request
  • Remote Transaction
  • Distributed Transaction
  • Distributed Request

Remote Request

  • A single request to a single remote site

SELECT * FROM atlserver.bankdb.customer

WHERE custcode = '12345';

remote transaction
Remote Transaction
  • Multiple data requests to a single remote site

BEGIN WORK;

INSERT INTO atlserver.bankdb.account

(accnum, acctype)

VALUES (789, 'C');

INSERT INTO atlserver.bankdb.cust_acct

(custnum, accnum)

VALUES (123, 789);

COMMIT WORK;

distributed transaction
Distributed Transaction
  • Multiple data requests to multiple sites

BEGIN WORK;

INSERT INTO osloserver.bankdb.employee

(empcode, emplname, …)

SELECT empcode, emplname, …

FROM atlserver.bankdb.employee

WHERE empcode = 123;

DELETE FROM atlserver.bankdb.employee

WHERE empcode = 123;

COMMIT WORK;

  • Two-phase commit

Database

Database

distributed request
Distributed Request
  • Multiple requests to multiple sites
  • Each request can access multiple sites

BEGIN WORK;

CREATE VIEW temp

(empcode, empfname, emplname, empsalary)

AS

SELECT empcode, empfname, emplname, empsalary

FROM atlserver.bankdb.employee

UNION

SELECT empcode, empfname, emplname, empsalary

FROM osloserver.bankdb.employee;

SELECT empcode, empfname, emplname, empsalary*.15 AS bonus

FROM temp;

UPDATE atlserver.bankdb.employee

SET empusdretfund = empusdretfund + 1000;

UPDATE osloserver.bankdb.employee

SET empkrnretfund = empkrnretfund + 7500;

COMMIT WORK;

distributed database design
Distributed database design
  • Horizontal Fragmentation
  • Vertical Fragmentation
  • Hybrid Fragmentation
  • Replication
distributed database24
Distributed Database

DEPT table resides on

HQ database, EMP table

is on Sales DB

replication
Replication
  • Full replication
    • Tables are duplicated at each of the sites
    • Increased data integrity
    • Faster processing
    • More expensive
  • Partial replication
    • Indexes replicated
    • Faster querying
    • Retrieval from the remote database
replication27
Replication
  • Identical remote databases
  • Parallel Processing
    • Distributed processing in a local environment

Database

Server

Database

Client

Database

Server

Application

Server

Database

Client

Client

Database

remote job entry
Remote job entry
  • Local storage
    • Often cheaper
    • Maybe more secure
  • Remote processing
  • Useful when a personal computer is:
    • too slow
    • has insufficient memory
    • software is not available
  • Some local processing
    • Data preparation
slide29

(Chapter 12:

What to know)

Ways to distribute data storage

(where you keep the data) and data processing (where the computer works on it)

Remote job entry:

local storage, remote processing

Personal database:

local storage, local processing

Host/terminal:

remote storage, remote processing

Client-server computing:

various distributions of local & remote

storage/processing

slide30

(Chapter 12,

what to know)

Alternative client-server

architectures…

Two-tier, thick client:

client does most of the application processing work; server provides data management and access functions

Three-tier, thin client:

application processing is re-assigned to an application server; thin client (often a browser) handles data presentation tasks; a database server handles data management functions

N-tier:

extends three-tier, with thin client having access to multiple application and database servers

slide31

(Chapter 12:

What to know)

Distributed database:

What is it?

data is located on different (and often heterogeneous) systems; the system catalog, which is itself distributed, maintains information about the location and structure of all the parts

Partitioning:

data can be partitioned (fragmented) horizontally (distributes records locally to where they’re needed), or vertically (distributes fields to spread the processing load); also note hybrid

Replication:

tables (“full rep”) or indexes (“partial rep”) can be duplicated across sites; synchronous vs. asynchronous replication

slide32

(Chapter 12:

What to know)

Distributed data access:

The details of the SQL in Chapter 12 are FYI… however, you should understand the possibilities:

Remote request:

an application issues a single request to a single remote site

Remote transaction:

multiple data requests to a single remote site

Distributed transaction:

multiple data requests to multiple sites – each request is for data on a single server

Distributed request:

multiple data requests to multiple sites–

each request may be for data at multiple sites