Database Reference
In-Depth Information
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A block is the unit of transfer of data between physical storage and the main
memory of the computer system; block addressing is the general technique for
finding records.
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Three major file organizations: heap, sequential, and hash.
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RAID technology improves data retrieval performance and reliability of disk
storage.
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Indexing with primary and secondary indexes forms the primary method for
performance improvement of database systems.
•
Other performance considerations include data clustering, denormalization,
data fragmentation, memory buffer management, and preconstructed joins.
REVIEW QUESTIONS
1. List the primary goals of the physical design process. Which ones are the most
important?
2. Describe very briefly the physical design components.
3. What are the major physical design tasks?
4. How is the data dictionary used to record the contents of the database
system? What are the types of information stored in the data dictionary?
5. Describe how rows of a relational table are stored in physical storage.
6. What is your understanding of file organization? What are the major types
of file organizations?
7. How does RAID technology improve reliability of disk storage?
8. What is a B-tree index? Explain with a simple example.
9. What is data clustering? How does it improve data access performance?
10. Distinguish between horizontal and vertical partitioning. State the conditions
under which each option is useful.
EXERCISES
1. Indicate whether true or false:
A. Physical design may ignore the features of the target DBMS.
B. Proper physical design ensures improved database performance.
C. File organization refers to how blocks are allocated to files.
D. A row in a relational table is the unit of data transfer from physical storage.
E. Sequential file organization is best if the most common operation is range
selection.
F. Data striping in RAID technology improves disk reliability.
G. You can build a secondary index only on certain fields in the file.
H. Denormalization increases data redundancy but improves data access
performance.
I. Most DBMSs automatically create primary indexes.
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