Question 40

The relational data model is

a.	an external data model
b.	an internal data model
c.	a physical data model
d.	a logical data model

Question 49

Which of the following statement(s) is(are) correct?

a.	Multi-level index is designed to reduce the search cost of index part with a reduction ratio of logarithm function.
b.	Multi-level index is guaranteed to have the search cost proportional to the number of levels inmulti-level index.
c.	Both a. and b. are correct.
d.	Neither a. nor b. is correct.

Question 50

_____________________ guarantee(s) that the number of index block accesses is equal to the level of the index structures.

a.	Dynamic hashing
b.	Multilevel index
c.	B-tree/B+-tree
d.	Multi-Way search tree

Question 51

______________________ guarantee(s) the access structure is always balanced when a lot of updates such as insertions and deletions of file records occur.

a.	B-tree/B+-tree
b.	Multilevel index
c.	Multi-Way search tree
d.	Dynamic hashing