1. Instructor 彭智勇 武汉大学软件工程国家重点实验室 电话:87653196

2. Book 经典原版书库 《Database System Implementation》 (斯坦福大学) 机械工业出版社
（美）Hator Garcia-Molina, Jeffrey.D.Ullman, Jennifer Widom 著
(斯坦福大学)
机械工业出版社

3. Marking Scheme Assignment (4) (练习,3次): 15%
Small Test (3) (小测验,3次): %
Final Examination (期末考试): 70%
Total %

4. Practice 安装PostgreSQL系统 分析PostgreSQL源代码 改进PostgreSQL系统

5. Database System Implementation
Hector Garcia-Molina
Jeffrey D. Ullman
Jennifer Widom

6. Chapter 1
Introduction to DBMS Implementation

7. Database Management System
A database management system (DBMS) is a powerful tool for creating and managing large amounts of data efficiently and allowing it to persist over long periods of time, safely.

8. Capabilities of a DBMS Persistent Storage Programming interface
allowing the user to access and modify data through a powerful query language.
Transaction Management
supporting concurrent access to data and resiliency ( i.e. recovering from failures or errors)

9. Terminology Review Data Database Query Relation Schema (Metadata)
A collection of data, well organized for access and modification, preserved over a long period.
Query
Relation
An organization of data into a two-dimensional table.
Schema (Metadata)
A description of the structure of the data.

10. A Simple DBMS: Megatron 2000
Megatron is a relational database management system which supports the SQL query language.

11. Megatron 2000 Implementation
The Relation Students(name, id, dept)
Data: /usr/db/students
Smith#123#CS
Johnson#522#EE ……
Schema: /usr/db/schema
Students#name#STR#id#INT#dept#STR
Depts#name#STR#office#STR ……

12. Execution of Megatron 2000 DBMS
dbhost> megatron2000
WELCOME TO MEGATRON 2000 !
& SELECT *
FROM Students #
name id dept
Smith CS
Johnson EE

13. & SELECT *
FROM Students
WHERE id>= 500 | HighID #
/usr/db/HighID
Johnson#522#EE

14. How Megatron 2000 Executes Queries
SELECT * FROM R WHERE <Condition>
Read the file schema to determine the attributes of relation R and their types.
Check that the <Condition> is semantically valid for R.
Display each of the attribute names as the header of a column, and draw a line.
Read the file named R, and for each line:
(a) Check the condition, and
(b) Display the line as a tuple, if the condition is true.

15. SELECT * FROM R WHERE <Condition> | T
Read the file schema to determine the attributes of relation R and their types.
Check that the <Condition> is semantically valid for R.
Read the file named R, and for each line:
(a) Check the condition, and
(b) Write the result to a new file /usr/db/T, if the condition is true.
4. Add to the file /usr/db/schema an entry for T that looks just like the entry for R, except that relation name T replaces R. That is, the schema for T is the same as the schema for R.

16. Example 1.2
SELECT office
FROM Students, Depts
WHERE Students.name = ‘Smith’ AND
Students.dept = Depts.name #
for (each tuple s in Students)
for (each tuple d in Depts)
if(s and d satisfy the WHERE-condition)
display the office value from Depts;

17. Problem (1) of Megatron 2000 Tuple layout on disk
The data layout on disk is not flexible. e.g., - Change string from ‘Cat’ to ‘Cats’ and we have to rewrite file
- ASCII storage is expensive
- Deletions are expensive

18. Problem (2) of Megatron 2000 Search expensive; no indexes
e.g., - Cannot find tuple with given key quickly
- Always have to read full relation

19. Problem (3) of Megatron 2000 Brute force query processing
Query-processing is not clever.
e.g., select *
from R,S
where R.A = S.A and S.B > 1000
- Do select first?
- More efficient join?

20. Problem (4) of Megatron 2000 No buffer manager
There is no buffer in main memory.
e.g., Need caching

21. Problem (5) of Megatron 2000
There is no concurrency control.

22. Problem (6) of Megatron 2000 No reliability e.g., - Can lose data
- Can leave operations half done

23. Problem (7) of Megatron 2000 No security e.g., - File system insecure
- File system security is coarse

24. Problem (8) of Megatron 2000 No application program interface (API)
e.g., How can a payroll program get at the data?

25. Problem (9) of Megatron 2000
Cannot interact with other DBMSs.

26. Problem (10) of Megatron 2000
Poor dictionary facilities

27. Problem (11) of Megatron 2000
No GUI

28. Overview of a Database Management System
administrator
User/application
transaction
commands
queries,
updates
DDL Commands
Query
Compiler
DDL Compiler
Transaction Manager
query plan
metadata statistics
metadata
Execution
engine
Logging and Recovery
Concurrency Control
Index, file, and
record requests
Index/file/rec-
Ord manager
log
pages
page commands
data,
metadata,
indexes
Buffer
manager
Lock
table
read/write pages
Storage
manager
Buffers
Storage

29. Storage Management
It is responsible for storing data, metadata, indexes, and logs.
An important storage management component is the buffer manager, which keeps portions of the data contents in main memory.

30. Query Processing
A user or an application program initiates query to extract data from the database. The query is parsed and optimized by a query compiler. The resulting query plan is executed by the execution engine.

31. Transaction Management
Logging and Recovery
Concurrency Control
Deadlock Resolution

32. Course Overview C2 Memory hierarchy Storage-Management Overview
C3 Storage of data elements
C4 one-dimensional indexes
C5 Multidimensional indexes
Query Processing
C6 Query Execution
C7 Query compiler and optimizer
Transaction-Processing
C8 System failures
C9 Concurrency control
C10 More about transaction management
Information integration

33. The course lets students know better ways of building a database management system.