1. Chapter 11 Database System Implementation Spring 2001 Prof. Sang Ho Lee School of Computing, Soongsil Univ. shlee@computing.soongsil.ac.kr

2. Chapter 12 Isn’t Implementing a Database System Simple? Relations Statements Results

3. Chapter 13 Introducing the Database Management System The latest from Megatron Labs Incorporates latest relational technology UNIX compatible

4. Chapter 14 Megatron 3000 Implementation Details Relations stored in files (ASCII) e.g., relation R is in /usr/db/R Smith # 123 # CS Jones # 522 # EE...

5. Chapter 15 Megatron 3000 Implementation Details Directory file (ASCII) in /usr/db/directory R1 # A # INT # B # STR … R2 # C # STR # A # INT …...

6. Chapter 16 Megatron 3000 Sample Sessions % MEGATRON3000 Welcome to MEGATRON 3000! & & quit %...

7. Chapter 17 Megatron 3000 Sample Sessions & select * from R # Relation R A B C SMITH 123 CS &

8. Chapter 18 Megatron 3000 Sample Sessions & select A,B from R,S where R.A = S.A and S.C > 100 # A B 123 CAR 522 CAT &

9. Chapter 19 Megatron 3000 Sample Sessions & select * from R | LPR # & Result sent to LPR (printer).

10. Chapter 110 Megatron 3000 Sample Sessions & select * from R where R.A < 100 | T # & New relation T created.

11. Chapter 111 Megatron 3000 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

12. Chapter 112 Megatron 3000 To execute “ select * from R where condition | T ”: (1) Process select as before (2) Write results to new file T (3) Append new line to dictionary

13. Chapter 113 Megatron 3000 To execute “ select A,B from R,S where condition ”: (1) Read dictionary to get R,S attributes (2) Read R file, for each line: (a) Read S file, for each line: (i) Create join tuple (ii) Check condition (iii) Display if OK

14. Chapter 114 What’s wrong with the Megatron 3000 DBMS?

15. Chapter 115 What’s wrong with the Megatron 3000 DBMS? Tuple layout on disk –Change string from ‘Cat’ to ‘Cats’ and we have to rewrite file –ASCII storage is expensive –Deletions are expensive

16. Chapter 116 What’s wrong with the Megatron 3000 DBMS? Search expensive; no indexes –Cannot find tuple with given key quickly –Always have to read full relation

17. Chapter 117 What’s wrong with the Megatron 3000 DBMS? Brute force query processing e.g., select * from R,S where R.A = S.A and S.B > 1000 - Do select first? - More efficient join?

18. Chapter 118 What’s wrong with the Megatron 3000 DBMS? No buffer manager e.g.,Need caching

19. Chapter 119 What’s wrong with the Megatron 3000 DBMS? No concurrency control

20. Chapter 120 What’s wrong with the Megatron 3000 DBMS? No reliability e.g.,- Can lose data - Can leave operations half done

21. Chapter 121 What’s wrong with the Megatron 3000 DBMS? No security e.g.,- File system insecure - File system security is coarse

22. Chapter 122 What’s wrong with the Megatron 3000 DBMS? No application program interface (API) e.g.,How can a payroll program get at the data?

23. Chapter 123 What’s wrong with the Megatron 3000 DBMS? Cannot interact with other DBMSs.

24. Chapter 124 What’s wrong with the Megatron 3000 DBMS? Poor dictionary facilities

25. Chapter 125 What’s wrong with the Megatron 3000 DBMS? No GUI

26. Chapter 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,…

27. Chapter 127 Course Overview Concurrency Control Correctness, locks,… Transaction Processing Logs, deadlocks,… Security & Integrity Authorization, encryption,… Distributed Databases Interoperation, distributed recovery,…

28. Chapter 128 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

29. Chapter 129 Course Details LECTURES: Tuesday 9:00 – 11:50 am TEXTBOOK: Garcia-Molina, Ullman, Widom; "DATABASE SYSTEM IMPLEMENTATION“, Prentice Hall, 2000 ASSIGNMENTS: Written homework assignments. No programming. Significant reading assignments GRADING: –3-4 times exams. (90%) –Attendance and homework (10%) WEB SITE: http://orion.soongsil.ac.kr (Please check it periodically for last minute announcements)

30. Chapter 130 Read Carefully Course prerequisite –Undergraduate database courses –A First Course in Database Systems J. Ullman and J. Widom, Prentice Hall, 1997 Should be familiar with –ER/Relational/OO Data models –Database design theory (FD, normalization, …) –Relational algebra, SQL, OQL, …

31. Chapter 131 Notice that This course requires considerable amount of self-reading. I do not cover every part of this book, but the exams do. My primary concern is about how to encourage you to study databases It will not be easy for you !!!