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What is magnetic disks?explain it?
Magnetic disk provides the bulk of secondary storage of modern computer system. The disk capacity is growing at over 50% per year. But the storage needs of large applications have also been growing very fast and in some case each faster than the growth rate of disk capacities. A large data base may need 100 of disks.
Physical characteristics of disk
Physical disks are relatively simple. Every disc platter has a flat circular shape
We can call magnetic disk as
Ø hard disk
Ø Floppy disk
The read write head keeps information on a sector magnetically as reversals of the direction of magnetization of the magnetic material. There might be hundreds of concentric tracks on a disc surface, having thousands of sectors.
What is meant by heuristic optimisation?Discuss the major heuristics that are applied during query optimisation.
Eliminate Columns Not Dependent On Key The Employee Relation satisfies - First normal form - As it has no repeating groups. Second normal form - As it do not have multi-a
For each m:n relationship type R, we make a new table (say S) to represent R. We also contain the primary key attributes of both the participating entity types as a foreign key att
Explain the integrity constraints: Not Null, Unique, Primary Key with an example each. Is the combination 'Not Null, Primary Key' a valid combination. Justify. Not Null - Shou
Why, generally does an object-oriented system use the relational DBMS? The reasons for using relational DBMS for OO systems could be any combination of following: a. Many or
I have a small project that contains 3 deliverable s. I have done the first one and I would like you to help me with second one
explain cascading rollback
Consider the subsequent relations for a database which keeps track of business trips of salespersons in a sales office: SALESPERSON (SSN, Name, start_year, Dept_no) TRIP (SSN, Fr
How do I begin
Determine the steps of path in association network You can analyse use of paths in association network in the following steps: Examine every operation and see what asso
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