ISRO-2017

Question

Q.Consider a table that describes the customers:

Customers(custid,name,gender,rating)

The rating value is an integer in the range 1 to 5 and only two values(male and female) are recorded for gender.Consider the query "how many male customers have a rating of 5" ? The best indexing mechanism appropriate for the query is

A) Linear hashing

B)Extensible Hashing

C)B+tree

D)Bit-mapped index

Comments

Bit-mapped index.

Due to fixed values of rating and gender each tuple can easily points to exact value .

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yes

A,B,C eliminate

As there are values from 1 to 5

and also selection for male and female

Answer 1

Since The rating value is an integer in the range 1 to 5

and only two values(male and female) (assume male=0 and female=1) are recorded for gender as we see both the values of rating as well as gender are fixed,the bit mapped indexing is best suitable.

hence option (d) is correct.