RDBMS

Outline
Introduction
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
Distributed DBMS © 1998 M. Tamer Özsu & Patrick Valduriez Page 4.

Architecture

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


ANSI/SPARC Architecture

Users

External External External External
Schema view view view

Conceptual Conceptual
view
Schema

Internal Internal view
Schema


Standardization
Reference Model
A conceptual framework whose purpose is to divide standardization
work into manageable pieces and to show at a general level how these
pieces are related to one another.
Approaches
Component-based
Components of the system are defined together with the
interrelationships between components.
Good for design and implementation of the system.
Function-based
Classes of users are identified together with the functionality that
the system will provide for each class.
The objectives of the system are clearly identified. But how do you
achieve these objectives?
Data-based
Identify the different types of describing data and specify the
functional units that will realize and/or use data according to these
views.

Conceptual Schema Definition
RELATION EMP [
KEY = {ENO}
ATTRIBUTES = {
ENO : CHARACTER(9)
ENAME : CHARACTER(15)
TITLE : CHARACTER(10)
}
]
RELATION PAY [
KEY = {TITLE}
ATTRIBUTES = {
SAL : NUMERIC(6)
}
]


Conceptual Schema Definition
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)
}
]


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

⇓
INTERNAL_REL EMPL [
INDEX ON E# CALL EMINX
FIELD = {
HEADER : BYTE(1)
E# : BYTE(9)
ENAME : BYTE(15)
TIT : BYTE(10)
}
]


External View Definition –
Example 1

Create a BUDGET view from the PROJ relation

CREATE VIEW BUDGET(PNAME, BUD)
AS SELECT PNAME, BUDGET
FROM PROJ


External View Definition –
Example 2

Create a Payroll view from relations EMP and
TITLE_SALARY

CREATE VIEW PAYROLL (ENO, ENAME, SAL)
AS SELECT EMP.ENO,EMP.ENAME,PAY.SAL
FROM EMP, PAY
WHERE EMP.TITLE = PAY.TITLE


DBMS Implementation
Alternatives
Distribution
Distributed
Peer-to-peer
multi-DBMS
Distributed DBMS

Client/server

Autonomy

Multi-DBMS

Federated DBMS
Heterogeneity

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

Dimensions of the Problem
Distribution
Whether the components of the system are located on the same
machine or not
Heterogeneity
Various levels (hardware, communications, operating system)
DBMS important one
data model, query language,transaction management
algorithms
Autonomy
Not well understood and most troublesome
Various versions
Design autonomy: Ability of a component DBMS to decide on
issues related to its own design.
Communication autonomy: Ability of a component DBMS to
decide whether and how to communicate with other DBMSs.
Execution autonomy: Ability of a component DBMS to execute
local operations in any manner it wants to.


Datalogical Distributed
DBMS Architecture

ES1 ES2 ... ESn

GCS

LCS1 LCS2 ... LCSn

LIS1 LIS2 ... LISn


Datalogical Multi-DBMS
Architecture

GES1 GES2 ... GESn

LES11 … LES1n GCS LESn1 … LESnm

LCS1 LCS2 … LCSn

LIS1 LIS2 … LISn


Timesharing Access to a Central
Database
Terminals or PC terminal emulators
• No data
storage
• Host
running all
software
Batch Response Network
requests
Communications
Application Software

DBMS Services

Database


Multiple Clients/Single Server
Applications Applications Applications

Client Client Client
Services Services Services
Communications Communications Communications

LAN
High-level Filtered
requests data only
Communications

DBMS Services

Database


Task Distribution
Application
QL Programmatic
Interface … Interface
Communications Manager
SQL result
query table
Communications Manager

Query Optimizer
Lock Manager
Storage Manager
Page & Cache Manager

Database


Advantages of Client-Server
Architectures
More efficient division of labor
Horizontal and vertical scaling of resources
Better price/performance on client machines
Ability to use familiar tools on client machines
Client access to remote data (via standards)
Full DBMS functionality provided to client
workstations
Overall better system price/performance


Problems With Multiple-
Client/Single Server

Server forms bottleneck
Server forms single point of failure
Database scaling difficult


Multiple Clients/Multiple Servers
directory Applications
caching Client
query decomposition Services
Communications
commit protocols

LAN

Communications Communications

DBMS Services DBMS Services

Database Database


Server-to-Server
SQL interface
Applications
programmatic
Client
interface Services
other application Communications
support
environments
LAN

Communications Communications

DBMS Services DBMS Services

Database Database


Peer-to-Peer
Component Architecture
USER PROCESSOR DATA PROCESSOR

Global Local System Local
External Conceptual Conceptual Log Internal
Schema Schema GD/D Schema Schema
User
requests Database

Local Recovery
User Interface

Semantic Data

Global Query

Local Query
Controller

Execution
Optimizer

Processor

Processor
Handler

Manager

Runtime
Monitor

Support
USER Global

System
responses


Components of a Multi-DBMS
USER
Global
Responses Requests
GTP GUI GQP

GS GRM GQO

Local Component Interface Processor Component Interface Processor Local
Request (CIP) (CIP) Request
s s

User Transaction Transaction User
D Interface Manager D Manager Interface
B Query
Scheduler B Scheduler
Query
M
Processor … M
Processor
Query Recovery Recovery Query
S Optimizer Manager S Manager Optimizer
Runtime Sup. Runtime Sup.
Processor Processor


Directory Issues
Type

Local & central Local & distributed
Global & central & non-replicated (?) & non-replicated
& non-replicated

Global & distributed
Local & central & non-replicated (?)
& replicated (?)

Location
Global & central
& replicated (?)
Local & distributed
& replicated

Global & distributed
& replicated
Replication


RDBMS

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