Emersonq2003

Outline
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Introduction Background Distributed DBMS Architecture
« Datalogical Architecture « Implementation Alternatives « Component Architecture

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Distributed DBMS Architecture Distributed Database Design Semantic Data Control Distributed Query Processing Distributed Transaction Management

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Distributed DBMS

Parallel Database Systems Distributed Object DBMSDatabase Interoperability Current Issues

© 1998 M. Tamer …zsu & Patrick Valduriez

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Architecture
n

Defines the structure of the system
« components identified « functions of each component defined « interrelationships and interactions between components

defined

Distributed DBMS

© 1998 M. Tamer …zsu & Patrick Valduriez

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ANSI/SPARCArchitecture
Users

External Schema

External view

External view

External view

Conceptual Schema

Conceptual view

Internal Schema

Internal view

Distributed DBMS

© 1998 M. Tamer …zsu & Patrick Valduriez

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Standardization
Reference Model
« A conceptual framework whose purpose is to divide standardization

work into manageable pieces and to show at a general levelhow these pieces are related to one another.

Approaches
u

« Component-based

Components of the system are defined together with the interrelationships between components. u Good for design and implementation of the system. « Function-based u Classes of users are identified together with the functionality that the system will provide for each class. u The objectives of the system areclearly identified. But how do you achieve these objectives? « Data-based u Identify the different types of describing data and specify the functional units that will realize and/or use data according to these views.
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Conceptual Schema Definition
RELATION EMP [ KEY = {ENO} ATTRIBUTES = {
ENO : CHARACTER(9) ENAME :CHARACTER(15) TITLE : CHARACTER(10)

} ] RELATION PAY [ KEY = {TITLE} ATTRIBUTES = {
TITLE SAL : CHARACTER(10) : NUMERIC(6)

} ]
Distributed DBMS © 1998 M. Tamer …zsu & Patrick Valduriez Page 4. 5

Conceptual Schema Definition
RELATION PROJ [ KEY = {PNO} ATTRIBUTES = {
PNO PNAME BUDGET LOC : : : : CHARACTER(7) CHARACTER(20) NUMERIC(7) CHARACTER(15)

} ] RELATION ASG [ KEY = {ENO,PNO}ATTRIBUTES = {
ENO PNO RESP DUR : : : :

CHARACTER(9) CHARACTER(7) CHARACTER(10) NUMERIC(3)

} ]
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Internal Schema Definition
RELATION EMP [ KEY = {ENO} ATTRIBUTES = {
ENO : CHARACTER(9) ENAME : CHARACTER(15) TITLE : CHARACTER(10)

]

}

⇓
E# : BYTE(9) ENAME : BYTE(15) TIT : BYTE(10)

INTERNAL_REL E [INDEX ON E# CALL EMINX FIELD = {

]
Distributed DBMS

}

© 1998 M. Tamer …zsu & Patrick Valduriez

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External View Definition Ð Example 1

Create a BUDGET view from the PROJ relation
CREATE VIEW BUDGET(PNAME, BUD) AS SELECT PNAME, BUDGET FROM PROJ

Distributed DBMS

© 1998 M. Tamer …zsu & Patrick Valduriez

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External View Definition Ð Example 2Create a Payroll view from relations EMP and TITLE_SALARY
CREATE AS VIEW SELECT FROM WHERE PAYROLL (EMP_NO, EMP_NAME, SAL) EMP.ENO,EMP.ENAME,PAY.SAL EMP, PAY EMP.TITLE = PAY.TITLE

Distributed DBMS

© 1998 M. Tamer …zsu & Patrick Valduriez

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DBMS Implementation Alternatives

Distributed DBMS

© 1998 M. Tamer …zsu & Patrick Valduriez

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Dimensions ofthe Problem
n

Distribution

« Whether the components of the system are located on the same

machine or not

n

Heterogeneity
u

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

data model, query language,transaction management algorithms

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Autonomy
u u u

« Not well understood and most troublesome « Various versions [Veijalainen and...