Quiz for Indexes

Q1: What is the main purpose of an index in a database?

A. To store foreign keys B. To ensure normalization C. To speed up query performance D. To enforce constraints

Q2: What is the primary purpose of an index in SQL?

A. To format tables B. To secure data C. To speed up data retrieval D. To normalize data

Q3: Which of the following types of indexes allows duplicate values?

A. Primary Index B. Unique Index C. Composite Index D. Clustered Index

Q4: What type of index physically reorders the data on the disk?

A. Non-clustered index B. Unique index C. Clustered index D. Bitmap index

Q5: Which index type allows multiple indexes on the same column?

A. Primary index B. Secondary index C. Foreign index D. Clustered index

Q6: Which statement is true about a unique index?

A. It allows NULLs only B. It enforces uniqueness of the column values C. It sorts the rows automatically D. It compresses column data

Q7: Which clause is used with CREATE INDEX to prevent duplicates?

A. NOT NULL B. DISTINCT C. UNIQUE D. PRIMARY

Q8: How can indexes improve performance?

A. By compressing data B. By duplicating data C. By optimizing SELECT queries D. By reducing table size

Q9: Can indexes slow down performance?

A. Yes, for SELECT queries B. Yes, during INSERT/UPDATE/DELETE C. No, they always improve performance D. Only in MySQL

Q10: Which of the following is true about clustered indexes?

A. A table can have multiple clustered indexes B. They store data randomly C. They define the physical order of data in a table D. They cannot be created on primary keys

Q11: Which of the following supports full-text indexing?

A. VARCHAR B. INT C. TEXT D. DATE

Q12: Which command is used to remove an index?

A. DROP TABLE B. DELETE INDEX C. DROP INDEX D. REMOVE INDEX

Q13: What is a composite index?

A. An index on a single column B. An index on multiple columns C. An index on foreign key only D. An index created by JOIN

Q14: Which index is automatically created on primary key?

A. Foreign index B. Secondary index C. Clustered index D. Bitmap index

Q15: When should you avoid creating indexes?

A. On columns used in WHERE clause B. On columns with low cardinality C. On columns with high read queries D. On primary key columns

Q16: Which column type is best for indexing?

A. Highly repetitive B. High cardinality C. Binary blob D. JSON

Q17: Which of the following can negatively impact index performance?

A. Proper normalization B. Index fragmentation C. Use of primary keys D. Use of foreign keys

Q18: What does the EXPLAIN command do in SQL?

A. Deletes indexes B. Shows execution plan C. Creates views D. Sorts data by index

Q19: Which of these can help reduce the size of an index?

A. Using clustered index B. Using shorter column length C. Using primary keys D. Using TEXT fields

Q20: Can an index be created on a computed column?

A. Yes, always B. No, never C. Only if deterministic D. Only for primary keys