2. 1.1 The Evolution of Database Systems
Database: a collection of data that is managed by a DBMS
The DBMS is expected to:
1) Specify the schema using a specialized data-definition language
2) Give users the ability to query and modify the data using data-manipulation language
3) Support the storage of very large amounts of data
4) Enable durability
5) Control access to data from many users at once (isolation and atomicity)
Database Systems

3. 1.1.1 Early Database Management Systems
The first commercial DBMS appeared in the late 1960’s.
File systems : only item (3) supported
Applications of DBMS:
1) Banking systems
2) Airline reservation systems
3) Corporate record keeping
Hierarchical model and network model
Database Systems

4. 1.1.2 Relational Database Systems
Since 1970, data systems change significantly.
Relations
SQL
Object-oriented features
Database Systems

5. 1.1.3 Smaller and Smaller Systems
Database systems available for even very small machines.
The use of documents often tagged using XML
Database Systems

6. 1.1.4 Bigger and Bigger Systems
Some important examples:
1) Google
2) Satellites
3) Flickr or Amazon
4) YouTube
5) Peer-to-peer file-sharing systems
Database Systems

7. 1.1.5 Information Integration
To build structures on top of existing databases
1) Data ware-houses
2) Middleware: an integrated model
Database Systems

8. 1.2 Overview of a Database Management System
(See Fig. 1.1)
Two distinct sources of commands:
1) Conventional users and application programs
2) A database administrator
Database Systems

9. 1.2 Overview of a Database Management System
Database Systems

10. 1.2.1 Data-Definition Language Commands
Metadata
Database Systems

11. 1.2.2 Overview of Query Processing
Two separate subsystems:
1) Answering the query
a. Buffer manager
b. Storage manager
2) Transaction processing
a. A concurrency-control manager, or scheduler,
responsible for assuring atomicity and isolation
of transactions
b. A logging and recovery manager, responsible
for the durability of transactions
Database Systems

12. 1.2.3 Storage and Buffer Managementms
The kinds of information:
1) Data
2) Metadata
3) Log records
4) Statistics
5) Indexes
Database Systems

13. 1.2.4 Transaction Processing
It is normal to group one or more database operations into a transaction, which is a unit of work.
The tasks performed by the transaction processor:
1) Logging
2) Concurrency control
3) Deadlock resolution
Database Systems

14. 1.2.5 The Query processor Two components:
1) Query compiler ⇒ query plan
a. Query parser
b. Query preprocessor
c. Query optimizer
2) Execution engine
Database Systems

15. 1.3 Outline of Database-System Studies
Five parts:
Relational database modeling
a. Functional dependencies and normalization
b. E/R model, UML, and ODL
2) Relational database programming
a. Relational algebra, Datalog
b. SQL
3) Semistructured data modeling and programming
a. XML, DTD, and XML schema
b. XPATH, XQuery, XSLT
Database Systems

16. 1.3 Outline of Database-System Studies
4) Database system implementation
a. Storage management
b. Query processing
c. Transaction processing
5) Modern database system issues
a. Search engines
b. Information integration
c. Data mining
d. Data-stream systems
e. Peer-to-peer systems
Database Systems

17. The End.
Database Systems