database system - ch01

The Worlds of Database SystemsThe Worlds of Database Systems

Prof. Yin-Fu HuangProf. Yin-Fu HuangCSIE, NYUST CSIE, NYUST

Chapter 1Chapter 1

Database Systems Yin-Fu Huang

1.11.1 The Evolution of Database SystemsThe 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 data4) Enable durability5) Control access to data from many users at once

(isolation and atomicity)


The first commercial DBMS appeared in the late 1960’s. File systems : only item (3) supported Applications of DBMS:

1) Banking systems2) Airline reservation systems3) Corporate record keeping

Hierarchical model and network model

1.1.11.1.1 Early Database Management SystemsEarly Database Management Systems


Since 1970, data systems change significantly. Relations SQL Object-oriented features

1.1.21.1.2 Relational Database SystemsRelational Database Systems


Database systems available for even very small machines.

The use of documents often tagged using XML

1.1.31.1.3 Smaller and Smaller SystemsSmaller and Smaller Systems


Some important examples:1) Google2) Satellites3) Flickr or Amazon4) YouTube5) Peer-to-peer file-sharing systems

1.1.41.1.4 Bigger and Bigger SystemsBigger and Bigger Systems


To build structures on top of existing databases1) Data ware-houses2) Middleware: an integrated model

1.1.51.1.5 Information IntegrationInformation Integration


1.21.2 Overview of a Database Management SystemOverview of a Database Management System

(See Fig. 1.1) Two distinct sources of commands:

1) Conventional users and application programs2) A database administrator


1.21.2 Overview of a Database Management SystemOverview of a Database Management System


Metadata

1.2.11.2.1 Data-Definition Language CommandsData-Definition Language Commands


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

1.2.21.2.2 Overview of Query ProcessingOverview of Query Processing


The kinds of information:1) Data2) Metadata3) Log records4) Statistics5) Indexes

1.2.31.2.3 Storage and Buffer ManagementmsStorage and Buffer Managementms


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 control3) Deadlock resolution

1.2.41.2.4 Transaction ProcessingTransaction Processing


Two components:1) Query compiler query plan⇒a. Query parserb. Query preprocessor

c. Query optimizer

2) Execution engine

1.2.51.2.5 The Query processorThe Query processor


1.31.3 Outline of Database-System StudiesOutline of Database-System Studies

Five parts:1) Relational database modeling

a. Functional dependencies and normalizationb. E/R model, UML, and ODL

2) Relational database programminga. Relational algebra, Datalogb. SQL

3) Semistructured data modeling and programminga. XML, DTD, and XML schemab. XPATH, XQuery, XSLT


1.31.3 Outline of Database-System StudiesOutline of Database-System Studies

4) Database system implementationa. Storage managementb. Query processingc. Transaction processing

5) Modern database system issuesa. Search enginesb. Information integrationc. Data miningd. Data-stream systemse. Peer-to-peer systems


The End.

database system - ch01

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