11. A secondary key is which of the following?

A. Nonunique key
B. Primary key
C. Useful for denormalization decisions
D. Determines the tablespace required

12. The fastest read/write time and most efficient data storage of any disk array type is:

A. RAID-0.
B. RAID-1.
C. RAID-2.
D. RAID-3

13. A rule of thumb for choosing indexes for a relational database includes which of the following?

A. Indexes are more useful on smaller tables.
B. Indexes are more useful for columns that do not appear frequently in the WHERE clause in queries.
C. Do not specify a unique index for the primary key of each table.
D. Be careful indexing attributes that have null values.

14. Sequential retrieval on a primary key for sequential file storage has which of the following features?

A. Very fast
B. Moderately fast
C. Slow
D. Impractical

15. A multidimensional database model is used most often in which of the following models?

A. Data warehouse
B. Relational
C. Hierarchical
D. Network