Databases questions
Consider a disk with the following characteristics: block size B = 128 bytes; number of blocks per track = 40; number of tracks per surface = 800. A disk pack consists of 25 double-sided disks. (Assume 1 block = 2 sector)
What is the total capacity of a track?
How many cylinders are there?
What are the total capacity of a cylinder?
What are the total capacity of the disk?
Suppose that the disk drive rotates the disk pack at a speed of 4200 rpm (revolutions per minute);
what are the transfer rate (tr) in bytes/msec?
What is the block transfer time (btt) in msec?
What is the average rotational delay (rd) in msec?
Suppose that the average seek time is 15 msec. How much time does it take (on the average) in msec to locate and transfer a single block, given its block address?
Calculate the average time it would take to transfer 25 random blocks, and compare this with the time it would take to transfer 25 consecutive blocks. Assume a seek time of 30 msec.
A PART file with Part-number as the key filed includes records with the following Part-number values: 23, 65, 37, 60, 46, 92, 48, 71, 56, 59, 18, 21, 10, 74, 78, 15, 16, 20, 24, 28, 39, 43, 47, 50, 69, 75, 8, 49, 33, 38.
Suppose that the search field values are inserted in the given order in a B+-tree of order p = 4 and Pleaf = 3; show how three will expand and what the final tree will look like.
Suppose the following search field values are deleted in the order from the B+-tree, show how the tree will shrink and show the final tree. The deleted values are: 75, 65, 43, 18, 20, 92, 59, 37.
Optimize the execution plan of the following query using rule based optimization.
SELECT P.number, D.num, E.lname
FROM EMPLOYEE E, DEPARTMENT D, PROJECT P
WHERE P.location = ‘Dammam’ AND E.sex = ‘M’ AND D.num = E.num AND D.mgr_ssn = E.ssn;
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