CS4432Notes 11 CS 4432 Database Systems II Lecture 1: Introduction

CS4432Notes 12 Recommended Background Beginning database knowledge as gained in say CS3431 Some knowledge of software engineering (Java), such as CS3733.

CS4432Notes 13 Staff INSTRUCTOR: Professor Murali Mani Office Hours: –Mondays 11:30 – 12:30. Thursdays 10: :30 am TEACHING ASSISTANTS –Di Wang Office hrs from webpage See course webpage ( for office location & hours.

CS4432Notes 14 Protocol for Communication 1.Come to Office Hours!! –We have many office hours spread throughout the week. This is *your* resource! Use it ! 2.Post to discussion board : mywpi 3. cs.wpi.edu –Expect *at least* a 24 hour response time

CS4432Notes 15 Details LECTURES: Monday, Tuesday, Thursday, Friday 9:00 - 9:50 pm AK233 TEXTBOOK: –Garcia-Molina, Ullman, Widom; "DATABASE SYSTEM IMPLEMENTATION”, or –“DATABASE SYSTEMS, THE COMPLETE BOOK” WEB SITE: – andhttp://my.wpi.edu – Please check website daily for last minute announcements.

CS4432Notes 16 Logistics ASSIGNMENTS: –3-5 Written Homework Assignments. PROJECTS: –2 – 3 Group Projects EXAMS: –2 Exams GRADING: –Midterm: : 25% –Final Exam : 25% –Homework Assignments: 20% –Projects: 30% –Class participation: +/-

CS4432Notes 17 More Details Late Policy: –No late anything will be accepted ! Note: –For special circumstance and under instructor discretion, one late submission of up to 48 hours may be granted. Cheating : –No cheating of any kind ! –If cheating identified, you will receive an F, and you will be reported to the proper WPI honesty board.

CS4432Notes 18 Planning Miscellaneous BS/MS Credit Database Projects: MQP or ISP DB Undergraduate Research Position Summer Research (WPI/CRA/etc).

CS4432Notes 19 Database Material at WPI CS 3431 CS 4432 CS 542CS 561CS525MQP/ISPDSRG B, C terms D term (alternate) Grad. DBAdvanced DB Selected DB Project DB Research at WPI SpringVariesAny timeyear round you are here DON’T TAKE!

CS4432Notes 110 Interested in Research ? Curious about Graduate School? Take opportunity to visit WPI GRAD 2006 ! Mar 19, Wed, Campus Center !

CS4432Notes 111 A Brief Pre-amble

CS4432Notes 112 Isn’t Implementing a Database System Simple? Relations Statements Results

CS4432Notes 113 Naïve Implementation Relations stored in files (ASCII) e.g., relation Students is in /usr/db/Students Smith # 123 # CS Jones # 522 # EE.... Students CS # Fuller Labs EE # Atwater Kent PH # Olin Hall.... Depts

CS4432Notes 114 Naïve Implementation Details Directory file (ASCII) in /usr/db/schema Students#name#STR#id#INT#dept#STR Depts#name#STR#office#STR...

CS4432Notes 115 Sample Query select Students.name,Depts.office from Students,Depts where Students.dept = Depts.name and Students.id > 300 # Smith # 123 # CS # CS # Fuller Labs Smith # 123 # CS # EE # Atwater Kent Smith # 123 # CS # PH # Olin Hall Jones # 522 # EE # CS # Fuller Labs Jones # 522 # EE # EE # Atwater Kent Jones # 522 # EE # PH # Olin Hall

CS4432Notes 116 Execution Process To execute “ select * from R where condition ”: (1) Read dictionary to get R attributes (2) Read R file, for each line: (a) Check condition (b) If OK, display

CS4432Notes 117 Yet Another Execution To execute “ select A,B from R,S where condition ”: (1) Read dictionary to get Students,Depts attributes (2) Read Students file, for each line: (a) Read Depts file, for each line: (i) Create join tuple (ii) Check condition (iii) Display if OK

CS4432Notes 118 What’s wrong ? Layout ? Tuple layout on disk Example: - Change string from ‘Cat’ to ‘Cats’ and we have to rewrite file - ASCII storage is expensive - Deletions are expensive

CS4432Notes 119 What’s wrong ? Search ? Search expensive; no indexes e.g.,- Cannot find tuple with given key quickly - Always have to read full relation

CS4432Notes 120 What’s wrong ? Brute force query processing e.g., select * from R,S where R.A = S.A and S.B > Do select first? - More efficient join?

CS4432Notes 121 What’s wrong ? No buffer manager e.g.,Need caching

CS4432Notes 122 What’s missing? No concurrency control

CS4432Notes 123 What’s wrong ? No reliability e.g.,- Can lose data - Can leave operations half done

CS4432Notes 124 What’s wrong ? No security e.g.,- File system insecure - File system security is coarse

CS4432Notes 125 System Structure Buffer Manager Query ParserUser User TransactionTransaction Manager Strategy Selector Recovery ManagerConcurrency Control File ManagerLogLock TableM.M. Buffer Statistical Data Indexes User DataSystem Data

CS4432Notes 126 Course Overview File & System Structure Records in blocks, dictionary, buffer management,… Indexing & Hashing B-Trees, hashing,… Query Processing Query costs, join strategies,… Crash Recovery Failures, stable storage,… Concurrency Control Correctness, locks,… Transaction Processing Logs, deadlocks,… Additional Topics If time permits …

CS4432Notes 127 Next time: The lowest layer : Hardware Read chapter 11