distirbuted database architecture

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Distributed DBMS Page 4. 1 1998 M. Tamer zsu & Patrick Valduriez

OutlineI IntroductionI Background Distributed DBMS Architecture Datalogical Architecture

Implementation Alternatives Component Architecture

Distributed DBMS Architecture Distributed Database Design Semantic Data Control Distributed Query Processing Distributed Transaction Management Parallel Database Systems Distributed Object DBMS Database Interoperability Current Issues


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I Defines the structure of the system components identified

functions of each component defined

interrelationships and interactions between componentsdefined

Architecture


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ANSI/SPARC Architecture

ExternalSchema

ConceptualSchema

InternalSchema

Internal view

Users

Externalview

Conceptualview

Externalview

Externalview


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Reference Model A conceptual framework whose purpose is to divide standardization

work into manageable pieces and to show at a general level how thesepieces are related to one another.

Approaches Component-based

N Components of the system are defined together with the

interrelationships between components.N Good for design and implementation of the system. Function-based

N Classes of users are identified together with the functionality thatthe system will provide for each class.

N The objectives of the system are clearly identified. But how do youachieve these objectives? Data-based

N Identify the different types of describing data and specify thefunctional units that will realize and/or use data according to these

views.

Standardization


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RELATION EMP [KEY = {ENO}

ATTRIBUTES = {ENO : CHARACTER (9)ENAME : CHARACTER (15)TITLE : CHARACTER (10)

}]RELATION PAY [

KEY = {TITLE}

ATTRIBUTES = {TITLE : CHARACTER (10)SAL : NUMERIC (6)

}]

Conceptual Schema Definition


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RELATION PROJ [KEY = {PNO}

ATTRIBUTES = {PNO : CHARACTER (7)PNAME : CHARACTER (20)BUDGET : NUMERIC (7)

}]RELATION ASG [

KEY = {ENO,PNO} ATTRIBUTES = {

ENO : CHARACTER (9)PNO : CHARACTER (7)RESP : CHARACTER (10)DUR : NUMERIC (3)

}]

Conceptual Schema Definition


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RELATION EMP [KEY = {ENO}

ATTRIBUTES = {ENO : CHARACTER (9)ENAME : CHARACTER (15)TITLE : CHARACTER (10)

}]

=========================================INTERNAL_REL EMPL [

INDEX ON E# CALL EMINXFIELD = {

HEADER : BYTE (1)E# : BYTE (9)ENAME : BYTE (15)TIT : BYTE (10)

}]

Internal Schema Definition


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Create a BUDGET view from the PROJ relation

CREATE VIEW BUDGET(PNAME, BUD) AS SELECTPNAME, BUDGET

FROM PROJ

External View Definition Example 1


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DBMS Implementation Alternatives

Distribution

Heterogeneity

Autonomy

Client/server

Peer-to-peer Distributed DBMS

Federated DBMS

Distributedmulti-DBMS

Multi-DBMS


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Dimensions of the ProblemI Distribution

Whether the components of the system are located on the samemachine or not

I Heterogeneity Various levels (hardware, communications, operating system) DBMS important one

N data model, query language,transaction management

algorithmsI Autonomy

Not well understood and most troublesome Various versions

N Design autonomy : Ability of a component DBMS to decide onissues related to its own design.

N Communication autonomy : Ability of a component DBMS todecide whether and how to communicate with other DBMSs.

N Execution autonomy : Ability of a component DBMS to executelocal operations in any manner it wants to.


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Datalogical Multi-DBMS

Architecture

...

GCS

GES 1

LCS 2 LCS n

LIS 2 LIS n

LES 11 LES 1 n LES n 1 LES nm

GES 2GES

n

LIS 1

LCS 1


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Timesharing Access to a CentralDatabase

Communications

DBMS Services

Network

Terminals or PC terminal emulators

Batchrequests Response

No datastorage

Hostrunning allsoftware

Application Software

Database


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Multiple Clients/Single Server

Communications

ClientServices

Applications

Communications

DBMS Services

LANHigh-levelrequests

Filtereddata only

Communications

ClientServices

Applications

Communications

ClientServices

Applications

Database


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Task DistributionApplication

Communications Manager

Communications Manager

Lock Manager

Storage Manager

Page & Cache Manager

Query Optimizer

QLInterface

ProgrammaticInterface

SQLquery

resulttable

Database


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Advantages of Client-Server Architectures

I More efficient division of laborI Horizontal and vertical scaling of resourcesI Better price/performance on client machinesI Ability to use familiar tools on client machinesI Client access to remote data (via standards)I Full DBMS functionality provided to client

workstationsI Overall better system price/performance


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Problems With Multiple-Client/Single Server

I Server forms bottleneckI Server forms single point of failureI Database scaling difficult


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Multiple Clients/Multiple Servers

Communications

ClientServices

Applications

LAN

I directoryI cachingI query decompositionI commit protocols

Communications

DBMS Services

Database

Communications

DBMS Services

Database


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Server-to-Server

Communications

DBMS Services

LAN

Communications

DBMS Services

I SQL interfaceI programmatic

interfaceI other application

supportenvironments

Communications

ClientServices

Applications

Database Database


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Peer-to-PeerComponent Architecture

Database

DATA PROCESSORUSER PROCESSOR

USER

Userrequests

System

responses

ExternalSchema

U s e r

I n t e r

f a c e

H a n

d l e r

GlobalConceptual

Schema

S e m a n

t i c

D a t a

C o n

t r o l l e r

G l o b a

l

E x e c u t

i o n

M o n

i t o r

SystemLog

L o c a

l R e c o v e r y

M a n a g e r

LocalInternalSchema

R u n

t i m

e

S u p p o r t

P r o c e s s o r

L o c a l

Q u

e r y

P r o c e s s o r

LocalConceptual

Schema

G l o b a

l Q u e r y

O p

t i m i z e r

GD/D


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Components of a Multi-DBMSGlobalRequestsResponses

D

BMS

UserInterface

QueryProcessorQuery

Optimizer

TransactionManager

Scheduler

RecoveryManager

Runtime Sup.Processor

USER

GTP GQP

GQOGS GRM

GUI

LocalRequests

Component Interface Processor(CIP)

D

BMS

UserInterface

QueryProcessorQuery

Optimizer

TransactionManager

Scheduler

RecoveryManager

Runtime Sup.Processor

LocalRequests

Component Interface Processor(CIP)


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Directory IssuesType

Location

Replication

Global & central& non-replicated

Local & central& non-replicated (?)

Global & distributed& non-replicated (?)

Local & distributed& non-replicated

Global & central& replicated (?)

Global & distributed& replicated

Local & distributed& replicated

Local & central

& replicated (?)

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