Transcript Architecture

Outline



Introduction
Background
Distributed DBMS Architecture
 Introduction to Database Concepts
 Alternatives in Distributed Database Systems
 Datalogical Architecture
 Implementation Alternatives
 Component Architecture







Distributed DBMS
Distributed Database Design (Briefly)
Distributed Query Processing (Briefly)
Distributed Transaction Management (Extensive)
Building Distributed Database Systems (RAID)
Mobile Database Systems
Privacy, Trust, and Authentication
Peer to Peer Systems
© 1998 M. Tamer Özsu & Patrick Valduriez
Page 4. 1
Alternatives in Distributed Database Systems
Distribution
Distributed
multi-DBMS
Peer-to-peer
Distributed DBMS
Client/server
Autonomy
Multi-DBMS
Federated DBMS
Heterogeneity
Distributed DBMS
© 1998 M. Tamer Özsu & Patrick Valduriez
Page 4. 2
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.

Distributed DBMS
© 1998 M. Tamer Özsu & Patrick Valduriez
Page 4. 3
Datalogical Distributed DBMS Architecture
ES1
ES2
...
ESn
ES: External Schema
GCS: Global Conceptual Schema
LCS: Local Conceptual Schema
LIS: Local Internal Schema
GCS
LCS1
LCS2
LIS1
LIS2
Distributed DBMS
...
...
LCSn
LISn
© 1998 M. Tamer Özsu & Patrick Valduriez
Page 4. 4
Datalogical Multi-DBMS
Architecture
LES11


GESn
GES2
LES1n
GCS
LESn1
…
LCS1
LCS2
…
LCSn
LIS1
LIS2
…
LISn
…
GES: Global External Schema
LES: Local External Schema
Distributed DBMS
...
GES1


LESnm
LCS: Local Conceptual Schema
LIS: Local Internal Schema
© 1998 M. Tamer Özsu & Patrick Valduriez
Page 4. 5
Timesharing Access to a Central
Database
• No data
storage
Terminals or PC terminal emulators
• Host
running all
software
Batch
requests
Response
Network
Communications
Application Software
DBMS Services
Database
Distributed DBMS
© 1998 M. Tamer Özsu & Patrick Valduriez
Page 4. 6
Multiple Clients/Single Server
Applications
Applications
Applications
Client
Services
Communications
Client
Services
Communications
Client
Services
Communications
LAN
High-level
requests
Filtered
data only
Communications
DBMS Services
Database
Distributed DBMS
© 1998 M. Tamer Özsu & Patrick Valduriez
Page 4. 7
Task Distribution
Application
QL
Interface
…
Programmatic
Interface
Communications Manager
SQL
query
result
table
Communications Manager
Query Optimizer
Lock Manager
Storage Manager
Page & Cache Manager
Database
Distributed DBMS
© 1998 M. Tamer Özsu & Patrick Valduriez
Page 4. 8
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
Distributed DBMS
© 1998 M. Tamer Özsu & Patrick Valduriez
Page 4. 9
Problems With MultipleClient/Single Server

Server forms bottleneck

Server forms single point of failure

Database scaling difficult
Distributed DBMS
© 1998 M. Tamer Özsu & Patrick Valduriez
Page 4. 10
Multiple Clients/Multiple Servers




directory
caching
query decomposition
commit protocols
Applications
Client
Services
Communications
LAN
Communications
Communications
DBMS Services
DBMS Services
Database
Distributed DBMS
Database
© 1998 M. Tamer Özsu & Patrick Valduriez
Page 4. 11
Server-to-Server



SQL interface
programmatic
interface
other application
support
environments
Applications
Client
Services
Communications
LAN
Distributed DBMS
Communications
Communications
DBMS Services
DBMS Services
Database
Database
© 1998 M. Tamer Özsu & Patrick Valduriez
Page 4. 12
Components of a Multi-DBMS
USER
Responses
Local
Requests
GTP
GUI
GQP
GS
GRM
GQO
Component Interface Processor
(CIP)
D
B
M
S
User
Interface
Transaction
Manager
Query
Processor
Scheduler
Query
Optimizer
Recovery
Manager
Runtime Sup.
Processor
Distributed DBMS
Global
Requests
Component Interface Processor Local
(CIP)
Requests
…
D
B
M
S
Transaction
Manager
User
Interface
Scheduler
Query
Processor
Recovery
Manager
Query
Optimizer
Runtime Sup.
Processor
© 1998 M. Tamer Özsu & Patrick Valduriez
Page 4. 13
Directory Issues
Type
Global & central
& non-replicated
Local & distributed
& non-replicated
Local & central
& non-replicated (?)
Global & distributed
& non-replicated (?)
Local & central
& replicated (?)
Location
Global & central
& replicated (?)
Local & distributed
& replicated
Replication
Distributed DBMS
Global & distributed
& replicated
© 1998 M. Tamer Özsu & Patrick Valduriez
Page 4. 14