1. BACS 485 Multi-User Database Processing

2. Lecture Objectives Learn the difference between single and multi-user database processing and understand the importance of multi- user issues Learn the different system architectures that can be used to support multi-user database processing and the pros and cons of each.

3. Teleprocessing Systems The classic mode of supporting multi- users. One computer One CPU “dumb” terminals classic “time sharing” setup bandwidth limitations cause interface to be primitive (text based)

4. Teleprocessing Systems

5. Client-Server Architecture Client-server involves several computers (at least 2) applications shifted to the client all computers connected in a network the ‘server’ provides a service, the ‘client’ uses the service multiple servers are possible, but each must process a single database to be considered “client-server”.

6. Client-Server Architecture

7. File-Sharing Architecture File-sharing distributes applications and DBMS to user computers. the “server” provides access to files only older and more primitive than client-server typically involves more file transfer overhead files locks during transfer limit usefulness as a transaction processing system useful for group of large read-only files

8. File-Sharing Architecture

9. Distributed Database Architecture The database itself is distributed the logical database is physically spread across several computers requires a distributed database management system (DDBMS) each computer can process requests to its portion of the data and can request data from other nodes all this is transparent to the user note the difference between distributed processing and distributed database.

10. Distributed Database Architecture

11. Types of Distributed Databases There are 4 basic combinations of distributed database: Nonparatitioned, Nonreplicated Partitioned, Nonreplicated Nonpartitioned, Replicated Partitioned, Replicated These can be applied in a variety of ways causing a continuum of choices.

12. Non-Partitioned Non-Replicated Database

13. Partitioned Non-Replicated Database

14. Non-Partitioned Replicated Database

15. Partitioned Replicated Database

16. Continuum of Distributed Alternatives