Questions from Database Systems

Q: How does the remapping of bad sectors by disk controllers affect data

How does the remapping of bad sectors by disk controllers affect data-retrieval rates?

Q: Operating systems try to ensure that consecutive blocks of a file are

Operating systems try to ensure that consecutive blocks of a file are stored on consecutive disk blocks. Why is doing so very important with magnetic disks? If SSDs were used instead, is doing so still...

Q: RAID systems typically allow you to replace failed disks without stopping access

RAID systems typically allow you to replace failed disks without stopping access to the system. Thus, the data in the failed disk must be rebuilt and written to the replacement disk while the system i...

Q: What is scrubbing, in the context of RAID systems, and

What is scrubbing, in the context of RAID systems, and why is scrubbing important?

Q: Suppose you have data that should not be lost on disk failure

Suppose you have data that should not be lost on disk failure, and the application is write-intensive. How would you store the data?

Q: In the variable-length record representation, a null bitmap is

In the variable-length record representation, a null bitmap is used to indicate if an attribute has the null value. a. For variable-length fields, if the value is null, what would be stored in the offse...

Q: Consider the employee database of Figure 2.17. Give an

Consider the employee database of Figure 2.17. Give an expression in the relational algebra to express each of the following queries: a. Find the ID and name of each employee who works for “Big Bank”....

Q: Explain why the allocation of records to blocks affects database-system

Explain why the allocation of records to blocks affects database-system performance significantly.

Q: List two advantages and two disadvantages of each of the following strategies

List two advantages and two disadvantages of each of the following strategies for storing a relational database: a. Store each relation in one file. b. Store multiple relations (perhaps even the entire...

Q: Explain what is meant by repetition of information and inability to represent

Explain what is meant by repetition of information and inability to represent in- formation. Explain why each of these properties may indicate a bad relational- database design.