Database Systems

Chapter 1The Worlds of Database Systems

Section 1.1 Evolution of Database Systems

The DBMS is expected to :1 . Allow users to create new databases and specify their schemas

( logical structure of the data ) , using a specialized data - definition language.

2 . Give users the ability to query the data ( a “query" is a question about the data ) and modify the data , using an appropriate language , often called a query language or data - manipulation language.

3 . Support the storage of very large amounts of data - many terabytes or more - over a long period of time , allowing efficient access to the data for queries and database modifications.

Evolution of Database Systems

The DBMS is also expected to:

4 . Enable durability , the recovery of the database in the face of failures , errors of many kinds , or intentional misuse .

5 . Control access to data from many users at once , without allowing unexpected interactions among users ( called isolation ) and without actions on the data to be performed partially but not completely ( called atomicity )

Some History

1.1.1 Early Database Management SystemsAdabas

1.1.2 Relational Database Systems – 1970E. F. Codd - Date

1.1.3 Smaller and Smaller Systems and XMLLarge collections of small documents tagged with XML serve as a database.

1.1.4 Bigger and Bigger SystemsPetabytes

1.1.5 Information Integration – joining information in many related databases into a whole

Data warehouses

Section 1.2Overview of a Database Management System

There is a difference between commands used by users and application programs,

and those used by a database administrator

1.2.1 Data-Definition Language CommandsDefining tables and restrictions on data

1.2.2 Overview of Query ProcessingAnswering the QueryTransaction Processing

1.2.3 Storage and Buffer Management1.2.3 Transaction Processing

The ACID Properties of Transactions

1.2.5 The Query ProcessorThe query compiler with parser, preprocessor, and optimizerThe execution engine

Section 1.3Outline of Database-System Studies

Part I Relational Database ModelingFunction dependencies and normalizationE/R model , UML, and Object Definition Language (ODL)

Part II: Relational Database ProgrammingRelational algebra and SQL

Part III: Semi-structured Data Modeling and ProgrammingXML because of the Web

Part IV: Database System ImplementationStorage management, query processing , transaction processing, logging and recovery

Part V: Modern Database System IssuesSearch engines and data mining