week1 lecture2 on DataBaseManagementSystem.ppt

Distributed DBMS © 2001 M. Tamer Özsu & Patrick Valduriez Page 1.1 Outline  Introduction What is a distributed DBMS Problems Current state-of-affairs  Background  Distributed DBMS Architecture  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

Distributed DBMS © 2001 M. Tamer Özsu & Patrick Valduriez Page 1.3 Database Management database DBMS Application program 1 (with data semantics) Application program 2 (with data semantics) Application program 3 (with data semantics) description manipulation control

Distributed DBMS © 2001 M. Tamer Özsu & Patrick Valduriez Page 1.4 Integrate Databases and Commuinication Database Technology Computer Networks integration distribution integration Distributed Database Systems

Distributed DBMS © 2001 M. Tamer Özsu & Patrick Valduriez Page 1.5 Distributed Computing  A number of autonomous processing elements (not necessarily homogeneous) that are interconnected by a computer network and that cooperate in performing their assigned tasks.

Distributed DBMS © 2001 M. Tamer Özsu & Patrick Valduriez Page 1.6  Synonymous terms distributed data processing multiprocessors/multicomputers satellite processing backend processing dedicated/special purpose computers timeshared systems functionally modular systems Peer to Peer Systems Distributed Computing

Distributed DBMS © 2001 M. Tamer Özsu & Patrick Valduriez Page 1.8 What is a Distributed Database System? A distributed database (DDB) is a collection of multiple, logically interrelated databases distributed over a computer network. A distributed database management system (D–DBMS) is the software that manages the DDB and provides an access mechanism that makes this distribution transparent to the users. Distributed database system (DDBS) = DB + Communication

Distributed DBMS © 2001 M. Tamer Özsu & Patrick Valduriez Page 1.9  A timesharing computer system  A loosely or tightly coupled multiprocessor system  A database system which resides at one of the nodes of a network of computers - this is a centralized database on a network node What is not a DDBS?

Distributed DBMS © 2001 M. Tamer Özsu & Patrick Valduriez Page 1.12 Implicit Assumptions  Data stored at a number of sites  each site logically consists of a single processor.  Processors at different sites are interconnected by a computer network  no multiprocessors parallel database systems  Distributed database is a database, not a collection of files  data logically related as exhibited in the users’ access patterns relational data model  D-DBMS is a full-fledged DBMS not remote file system, not a TP system

Distributed DBMS © 2001 M. Tamer Özsu & Patrick Valduriez Page 1.13 Shared-Memory Architecture Examples : symmetric multiprocessors (Sequent, Encore) and some mainframes (IBM3090, Bull's DPS8) P1 Pn M D

Distributed DBMS © 2001 M. Tamer Özsu & Patrick Valduriez Page 1.15  Manufacturing - especially multi-plant manufacturing  Military command and control  Electronic fund transfers and electronic trading  Corporate MIS  Airline restrictions  Hotel chains  Any organization which has a decentralized organization structure Applications

Distributed DBMS © 2001 M. Tamer Özsu & Patrick Valduriez Page 1.16  Transparent management of distributed, fragmented, and replicated data  Improved reliability/availability through distributed transactions  Improved performance  Easier and more economical system expansion Distributed DBMS Promises

Distributed DBMS © 2001 M. Tamer Özsu & Patrick Valduriez Page 1.17 Transparency  Transparency is the separation of the higher level semantics of a system from the lower level implementation issues.  Fundamental issue is to provide data independence in the distributed environment  Network (distribution) transparency  Replication transparency  Fragmentation transparency  horizontal fragmentation: selection  vertical fragmentation: projection  hybrid

Distributed DBMS © 2001 M. Tamer Özsu & Patrick Valduriez Page 1.18 Example TITLE SAL PAY Elect. Eng. 40000 Syst. Anal. 34000 Mech. Eng. 27000 Programmer 24000 PROJ PNO PNAME BUDGET ENO ENAME TITLE E1 J. Doe Elect. Eng. E2 M. Smith Syst. Anal. E3 A. Lee Mech. Eng. E4 J. Miller Programmer E5 B. Casey Syst. Anal. E6 L. Chu Elect. Eng. E7 R. Davis Mech. Eng. E8 J. Jones Syst. Anal. EMP ENO PNO RESP E1 P1 Manager 12 DUR E2 P1 Analyst 24 E2 P2 Analyst 6 E3 P3 Consultant 10 E3 P4 Engineer 48 E4 P2 Programmer 18 E5 P2 Manager 24 E6 P4 Manager 48 E7 P3 Engineer 36 E8 P3 Manager 40 ASG P1 Instrumentation 150000 P3 CAD/CAM 250000 P2 Database Develop. 135000 P4 Maintenance 310000 E7 P5 Engineer 23

Distributed DBMS © 2001 M. Tamer Özsu & Patrick Valduriez Page 1.19 Transparent Access SELECT ENAME,SAL FROM EMP,ASG,PAY WHERE DUR > 12 AND EMP.ENO = ASG.ENO AND PAY.TITLE = EMP.TITLE Paris projects Paris employees Paris assignments Boston employees Montreal projects Paris projects New York projects with budget > 200000 Montreal employees Montreal assignments Boston Communication Network Montreal Paris New York Boston projects Boston employees Boston assignments Boston projects New York employees New York projects New York assignments Tokyo

week1 lecture2 on DataBaseManagementSystem.ppt

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week1 lecture2 on DataBaseManagementSystem.ppt