Exercise 6: Using Indexes

DSCB Ex. 15.6.2.

Suppose B(R) = 10,000 and T(R) = 500,000. Let there be an index on R.a, and let V(R.a) = k for some number k. Give the cost of σ_a=0(R), as a function of k, under the following circumstances. You may neglect disk I/O’s needed to access the index itself.

a) The index is clustering

b) The index is not clustering

c) R is clustered, and the index is not used.

DSCB Ex. 15.6.3.

Repeat Ex. 15.6.2. if the operation is the range query σ_{C<=a AND a<=D}(R). You may assume that C and D are constants such that k/10 of the values are in the range.