Question

1.Consider a hard drive with an average seek time of 9 ms. Its disk spins at 7200 rpm. What’s the
average access time? In your answer, ignore the drive transfer time and any controller overhead.
2.Suppose that we are using extendable hashing on a file that contains records with the following
search-key values: (2, 3, 5, 7, 11, 17, 19, 23, 29, 31). Show the final extendable hash structure for
this file if the hash function is h(x) = x mod 8 and buckets can hold three records. Recall that:
a. the bucket address table is indexed by the prefix of the binary representation of h(x).
b. Initially i = 0, i.e. the prefix consists of zero bits. There is only one bucket. There is one entry
in the address table whose key = null (since prefix size = 0) with a pointer that points to the
only bucket we have.
3.What’s the difference between open and closed hashing? Which one is used in database
applications, and why?
4.Construct a B+-tree for the following set of values: (2, 3, 5, 7, 11, 17, 19, 23, 29, 31). Assume that
the tree is initially empty and the values are added in ascending order. Let the degree of the tree be
four, i.e. at most four pointers are allowed in any node. In your answer show the final tree.
5.Show your tree from from question 4 mentioned above we insert 10.
6.Show your tree from from question 4 mentioned above we delete 19.

Answer 1