Database Management Systems
Assignment 1
To verify the effect of data organization on I/O time we want to have a practical test. To avoid
optimizations by the compiler we will use raw file I/O function fread/fwrite in C.
Create a text file on the hard disk of your computer. Your file should have 100,000 records. Each record
should be of 1024 bytes. You may define the record format using a struct as:
strcut MyRecord
{
int ID;
char Name[1020];
};
Create a variable of type MyRecord, copy some string into the Name field.
Now create a file in binary mode (wb) and write this record into it 100,000 times, put the loop variable in
the ID field of the variable. We use binary mode to have the same length for records inside the file.
Close the file, and open it in read/write mode (r+b).
Case 1:
Start timer, read all 100,000 blocks. What was the total time?
Case 2:
Start timer, in a loop that repeats 100,000 times, generate random numbers, read the block. What was
the total time?
Hint: to read block n, you can use fseek function to go to the block then read it. Use (n-1)*1024 to find
the offset of the block from the beginning of the file
Repeat Case 1 and Case 2. Do you get different timings? Why?
Deliverable:
Write a report about your experiments. Put your code in the report. Discuss your results and findings.
Save your report in pdf format, and submit it through BB.
