1. BBM371 Data Managment Assoc. Prof. Dr. Ebru Akçapınar Sezer
@Ebru176

2. Outline Tree based Storage devices Basic file and DBMS concepts
Record/page formats
Layers of DBMS
Journey of byte
Indexing
Traditional/multilevel
Tree based
Hash based
External sorting
Spatial Indexing

3. Policies Class attendance is strongly recomended
One midterm (%25), 3 quiz, 2 attandance quiz and ofcourse one final (%50) exam
No homework, trust comes first
Think about that this is not an «elective course»
Presentation based, question and answer style
Text book:
Raghu Ramakrishnan, Database Management Systems, McGraw Hill, (text book).
R. Elmasri, S.B. Navathe, Fundamentals of Database Systems, 4th edition, Addison-Wesley, 2004.
Office hour: whenever you come to my office

4. From Data Str 2 File Str Similar points: Different perspectives:
Representation of Data +
Operations for accessing data
Different perspectives:
Data structures: deal with data in main memory
File structures: deal with data in secondary storage

5. First «Data» What is DATA?
Data are any facts, numbers, or text that can be processed by a computer
What is Managment
Set of activities to accomplish desired goals and objectives using available resources efficiently and effectively.
And so… Data Managment is
To choose data storage policy which satisfies end user’s specified requirements and minimizes the response time

6. Store data in «where» Up to now : In memory
Arrays, linked lists, ques, stack, heaps….
After today: In memory and in files
What are we doing?
dealing with huge data
let’s think about the larger data than your available memory, can you use arrays ?

7. File means «KÜTÜK», not «Dosya» !!!
has format, size, file processor depends on format
stores data
image, video, pdf, source code, etc
Not interested in all types of data, specialize on the «data about entity»

8. Let’s place the FS in our domain?
Application
DBMS
File system
Operating System
Hardware

9. Secondary Storage (SS)
MM versus SS
processing
Main Memory (MM)
data is manipulated here
- Semiconductors
- fast, expensive,volatile, small
data transfer
storage
Secondary Storage (SS)
data is stored here
data transfer
- disks, tape
-slow, cheap, stable, large

10. MM versus SS
data is manipulated here
- Semiconductors
- Fast, expensive, volatile, small
Main Memory (MM)
Minimize the number of trips to the disk in order to get desired information
Grouping related information so that we are likely to get everything we need with only one trip to the disk.
processing
data transfer
storage
Secondary
Storage (SS)
- disks, tape
- Slow,cheap, stable, large
data is stored here

11. How fast is main memory? Typical time for getting info from:
Main memory: ~12 nanosec = 120 x 10-9 sec
Magnetic disks: ~30 milisec = 30 x 10-3 sec

12. Physical Files and Logical Files
physical file: a collection of bytes stored on a disk or tape
logical file: a channel connecting program to a physical file
The physical file has a name, for instance myfile.txt
The logical file has a logical name inside the program.
In C : FILE *outfile;
In C++ : fstream outfile;
The program (application) sends (or receives) bytes to (from) a file through the logical file. The program knows nothing about where the bytes go (came from).
The operating system is responsible for associating a logical file in a program to a physical file in disk or tape. Writing to or reading from a file in a program is done through the operating system.