File structures (sequential files, indexing, B and B+ trees)

Question 31

In the index allocation scheme of blocks to a file, the maximum possible size of the file depends on :

• the size of the blocks, and the size of the ad­dress of the blocks.

• the number of blocks used for the index, and the size of the blocks.

• the size of the blocks, the number of blocks used for the index, and the size of the address of the blocks.

• None of these

Question 32

An index is clustered, if

• it is on a set of fields that form a candidate key.
• it is on a set of fields that include the primary key.
• the data records of the file are organized in the same order as the data entries of the index.
• the data records of the file are organized not in the same order as the data entries of the index.

Question 33

Which of the following related to snowflake schema is true?

• Each dimension is represented by a single dimensional table
  

• Maintenance efforts are less
  

• Dimension tables are normalised
  

• It is not an extension of star schema
  

Question 34

A database table T1 has 2000 records and occupies 80 disk blocks. Another table T2 has 400 records and occupies 20 disk blocks. These two tables have to be joined as per a specified join condition that needs to be evaluated for every pair of records from these two tables. The memory buffer space available can hold exactly one block of records for T1 and one block of records for T2 simultaneously at any point in time. No index is available on either table. If Nested-loop join algorithm is employed to perform the join, with the most appropriate choice of table to be used in outer loop, the number of block accesses required for reading the data are  

• 800000

• 40080

• 32020

• 100

Question 35

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

• Linear hashing
• Extendible hashing
• B+ Tree
• Bit-mapped hashing

Question 36

In a Hierachical database, a hashing function is used to locate the ________.

• Collision
• Root
• Foreign Key
• Records