1. Welcome to …..
File Organization

2. Data and File organization
Instructor: Dr Halla Abdel Hameed
Objectives of the Course and Preliminaries

3. Objectives of The Course
To Provide a Solid Introduction to the Topic of File Structures Design.
To Discuss a number of Advanced Data Structure Concepts that are necessary for achieving high efficiency in File Operations.
To Develop important programming skills in and Object-Oriented Language such as C++ or Java.
January 10, 2000

4. Pre-Requisites Introduction to Computer Science. Knowledge of C++
Course Link…..
January 10, 2000

5. Required TextBook Title: File Structures
An Object-Oriented Approach with C++
Authors:
Michael J. Folk
Bill Zoellick
Greg Riccardi
January 10, 2000

6. Course Requirements
Lab Work (Programming assignments or A Programming Project + oral Exam) (25%)
A Mid-Term (10%)
A Final Exam (65%)
January 10, 2000

7. Special Thank to Eng. Mostafa Elmasri for his contribution in preparing this material.

8. Course Outline Introduction To File Management
Fundamental File Processing Operations
Secondary Storage, Physical Storage Devices: Disks, Tapes And CD-ROM.
fundamental file structure .
Managing Files Of Records.
Organizing file for performance (File Compression- Reclaiming Space In Files- Internal Sorting- Binary Searching- Keysorting).
Indexing.
Consequential Processing And Eternal Sorting
Multilevel Indexing And B Trees
Indexed Sequential Files And B+trees.
Hashing And Extendible Hashing.

9. Course Outline Introduction To File Management
Fundamental File Processing Operations
Secondary Storage, Physical Storage Devices: Disks, Tapes And CD-ROM.
fundamental file structure .
Managing Files Of Records.
Organizing file for performance (File Compression- Reclaiming Space In Files- Internal Sorting- Binary Searching- Keysorting).
Indexing.
Consequential Processing And Eternal Sorting
Multilevel Indexing And B Trees
Indexed Sequential Files And B+trees.
Hashing And Extendible Hashing.

10. All this will be built on your knowledge of Data structure
Data Processing from computer science perspective:
Storage of data
Organization of data
Access to data
Processing of data
All this will be built on your knowledge of Data structure

12. File Organization Lecture 1
Introduction to the Design and Specification of File Structures
File Organization

13. Lecture Objectives
Introduce the primary design issues that characterize file structure design.
Survey the history of file structure.
Introduce conceptual toolkit for file structure design.
Develop an object-oriented toolkit that makes file structure easy to use.

14. Lecture Contents The heart of file structure design.
A short history of file structure design.
A conceptual toolkit: File structure literacy.
An object-oriented toolkit: Making file structure usable.

15. The heart of file structure design
Section 1.1
The heart of file structure design

16. File Structure Definition & Functions
A combination of representations for data in files and of operations for accessing the data.
Functions
Allowing applications to read, write and modify data.

18. Memory versus Secondary Storage
Secondary storage such as disks can pack 1000’s of megabytes in a small physical location.
Computer Memory (RAM) is limited.
Comparing to Memory, access to secondary storage is extremely slow.
Getting information from slow RAM takes seconds (= 120 nanoseconds) while getting information from Disk takes seconds (= 30 milliseconds)
Roughly,
20 second on RAM ≈ 58 days on Disk

19. Improve Secondary Storage Access Time
representation of the data
the implementation of the operations
⇒ the efficiency of the file structure for particular applications

20. General Goals Get the information we need with one access to the disk.
If that’s not possible, then get the information with as few accesses as possible.
Group information so that we are likely to get everything we need with only one trip to the disk.

21. A short history of file structure design
Section 1.2
A short history of file structure design

22. Early Work Early Work assumed that files were on tape.
Access was sequential and the cost of access grew in direct proportion to the size of the file.

23. The emergence of Disks and Indexes
As files grew very large, unaided sequential access was not a good solution.
Disks allowed for direct access.
Indexes made it possible to keep a list of keys and pointers in a small file that could be searched very quickly.
With the key and pointer, the user had direct access to the large, primary file.

24. The emergence of Tree Structures
As indexes also have a sequential flavor, when they grew too much, they also became difficult to manage another problem was the changing of files.
The idea of using tree structures to manage the index emerged in the early 60’s.
Trees can grow very fast as records are added and deleted
resulting in long searches requiring many disk accesses to find a record.

25. Hash Tables
Retrieving entries in 3 or 4 accesses is good, but it does not reach the goal of accessing data with a single request.
From early on, Hashing was a good way to reach this goal with files that do not change size greatly over time.
Recently, Extendible Dynamic Hashing guarantees one or at most two disk accesses no matter how big a file becomes.

26. A conceptual toolkit: File structure literacy
Section 1.3
A conceptual toolkit: File structure literacy

27. Conceptual tools For File Structure Design
Tree
Structure
Direct
Access
Sequentially
Decrease the number of disk accesses by collecting data into buffers, blocks, or buckets.
Manage their growth by splitting them.
Find a way to increase our address or index space.
Find new ways to combine the basic tools.

28. Intended Learning Outcomes
After completing the course, the student will be able to:
Demonstrate knowledge of storage by describing how data is saved on disk.
Demonstrate knowledge of how file organization allows applications to read, write and modify data.
Demonstrate knowledge of cost-based query optimization by finding the data that match some search criteria.

29. Lecture Style New Lecture
Previous Lecture
A brief review of the previous lecture.
Answer questions addressed to instructor’s .
New Lecture
Introduce and explain current lecture topics.
Next Lecture
Follow up practice and tutorial scheme.
A brief proposal for the next lecture

30. Next Lecture

31. Fundamental File Processing Operations
Physical and logical file.
Opening and closing files.
Reading and writing.
Seeking.
Special Characters in files.
Physical devices and logical files.
File-related header files.

32. Questions?