CMPUT 291 File and Database Management Systems

Transcription

1 CMPUT 291 File and Database Management Systems Instructor: Davood Rafiei University of Alberta *Disclaimer: The slides used in the course may contain some of the slides provided by the authors of the adopted textbook (present and past) and those used in previous editions of this course by other instructors. 1

2 Lectures: Class Information Tue and Thu 9:30 10:50am in MEC 3 1 Instructors: Davood Rafiei (drafiei@cs.ualberta.ca) Office hours: Tue, Thu 1:00-2:00 p.m., ATH 355 TA s: Reza Sherkat Ananth Venkateswaran? 2

3 Labs Location: CSC 219 Schedule: Mon 14:00-15:20 (D01) Mon 15:30-16:50 (D02) Thu 14:00-15:20 (D03) Oracle DBA: Carolyn and Shauna at Contact them if something goes wrong with Oracle and you cannot resolve it with TA's or on the newsgroup. 3

4 Textbook and Slides Required Text: Kifer, Bernstein, Lewis, Database Systems : An Application Oriented Approach, 2 nd edition, Addison Wesley, 2005 Recommended Text: Ramakrishnan and Gehrke, Database Management Systems, 3 rd ed, McGraw- Hill, 2002 Slides, readings and schedule: Check the link Schedule at 4

5 Evaluation, etc. Assignments:15% total A1: 7%, A2: 8% Available 2 weeks before deadlines Quizzes: 5% total 2 in the lab and 2 in lectures Mini-Project 1: 15% (groups of 2) Available 4 weeks in advance Mini-Project 2: 10% (groups of 2) Available 2 weeks in advance Term Test: 25% Final Exam: 30% Newsgroup: ualberta.courses.cmput.291 5

6 Course Outline What are they and why are they useful? separate data from programs. factor out common pieces from applications. How can I use them? structuring data: relational data model queries: SQL How do they work? Components of a DBMS Implementation techniques Performance issues 6

7 What is a Database? A database is a very large, integrated collection of data. Models real-world enterprise. Entities (e.g. students, courses) Relationships (e.g. Jean Chretien is taking 291). Manufacturing University Hospital Bank Product data Student data, courses Patient data, facilities Account data 7

8 What is a DBMS? A Database Management System (DBMS) is a software package designed to store and manage databases. 8

9 Non-Database Approach Common in 60 s. One data set per program. Programmer defines (and implements) storage structures, access methods, etc. PROGRAM 1 Data Management DATA SET 1 PROGRAM 2 Data Management DATA SET 2 PROGRAM 3 Data Management DATA SET 3 9

10 Problems With more and more applications we get many files with different structures redundant storage inconsistent copies expensive updates incorrect data data exchange between applications 10

11 Database Approach PROGRAM 1 PROGRAM 1 DBMS Query Processor Transaction Mgr Integrated Database PROGRAM 2 11

12 Basic Idea Remove details related to data storage and access from application programs. Concentrate those functions in a single system called database management system. Have all applications access data through the DBMS. 12

13 Why Use a DBMS? Reduced redundancy Less risk of inconsistency Reduced application development time Uniform data administration Concurrent access, recovery from crashes But, most importantly Data Independence 13

14 Three Schema Levels Schema: a description of the data contents, structures and other aspects. External schema: what appl. programs and users see. Conceptual schema: description of the logical structure of data. Physical schema: file structures and indexes being used. Application 1 Application 2 Application 3 View 1 View 2 View 3 Conceptual Schema Physical Schema 14

15 Example: University Database External Schema (View): Course_info(cid:string,enrollment:integer) Conceptual schema: Students(sid: string, name: string, login: string, age: integer, gpa:real) Courses(cid: string, cname:string, credits:integer) Enrolled(sid:string, cid:string, grade:string) Physical schema: Relations stored as unordered files. Index on first column of Students. 15

16 Data Independence Objective: Application programs unaffected by changes in storage structure and access strategy. Logical data independence: Protection from changes in logical structure of data. Physical data independence: Protection from changes in physical structure of data. * One of the most important benefits of using a DBMS! 16

17 DBMS Functionality Data definition facilities provides a data definition language (DDL), stores the definitions in a user-accessible catalog (data dictionary). Data manipulation facilities provides a query language for storing, retrieving and updating data. Facilities for integrity constraints does the validation check for integrity constraints before updates, different kinds of constraints primary key constraints (entity integrity), foreign key constraints (no dangling references), check constraints. 17

18 DBMS Functionality (cont d) Provides concurrency control multiple users simultaneously access/update a database. Support transactions a sequence of user operations to be performed as an atomic action, all operations or none are performed. Provides database recovery whatever happens, never lose data. Provides query optimization find the best possible plan for executing a query. 18

19 Place in a Computer System Application Programs App. development tools DBMS Operating System Hardware 19

20 Why Study Databases??? Shift from computation to information Data is everywhere Have doubt? Check the Web! Datasets increasing in diversity and volume. Digital libraries, interactive video, Human Genome project, etc. It is a real challenge to manage this diversity and volume. It is also fun! 20

21 Course Outline What are they and why are they useful? Introduction How can I use them? Relational Model ER Model Relational Query Languages Database Design How do they work? Secondary Storage Basic File Structures Physical Database Design 21

22 Summary Introduced databases and DBMS Reviewed some functionalities of a DBMS and benefits Three-layered schema architecture Not sold yet? Google returns 8.5 million hits for DBA jobs Good DBAs are well-paid! DBMS R&D is one of the broadest and exciting areas in CS 22