Question

Which of the following statements about clustered indexes is FALSE?

Select one:

a. Creating two different clustered indexes on a table is a good strategy if the table contains multiple key columns

b. Clustered indexes do not work as well on columns that allow null values

c. Primary key columns are good candidates for clustered indexes

d. Clustered indexes are best used on columns whose values are unique

Answer 1

a) False

It is not possible to create multiple clustered indexes for a single table.
because clustered index reorders the table, arranging the data according to the index key.
This results in good performance when you worry about one particular column.
But if you want to order data by more than one column at that time you can not use a clustered index.
so you can create unclustered index on multiple columns results in increase performance.

b) If clustered index is not unique, SQL Server creates a 4-byte uniqueifier & add it to the clustered index value.
for clustered index, the column not need to be unique or without null.
A column with duplicates and null values is fine for creating a clustered index.

c) True

because it uniquely identifies every row in the table without the need for additional data.

d) True

declare the clustered index key column as unique to improve the queries performance.