Index — Learn free · DataAI Nexus

Self-check

Questions 1–10 of 10

1. What is the purpose of a database index?
Question 1A. To enforce foreign key relationshipsB. To compress table data on diskC. To store a backup copy of the tableD. To partition the table across nodesE. To enhance the performance of database queries on tables
2. What happens if a table has more indexes than it needs?
Question 2A. Query performance always improves furtherB. Performance can decreaseC. The table becomes read-onlyD. The primary key is droppedE. Nothing changes, because unused indexes are ignored
3. When is an index normally created on a table?
Question 3A. Before any data has been loadedB. Only when the table is archivedC. Only after a backup has been takenD. When the database starts growingE. Only when the table is partitioned
4. In the Library of Congress analogy for indexing, roughly how many items does the library hold?
Question 4A. About 170 millionB. About 17 millionC. About 1.7 billionD. About 70 millionE. About 700 thousand
5. What does the Library of Congress analogy illustrate about why indexes are needed?
Question 5A. That libraries need more staff than databasesB. That every book must be stored in alphabetical orderC. That an index contains all the information needed to access items quickly and efficiently, just as a database index does for dataD. That searching manually is faster than searching by computerE. That large collections should be split across buildings
6. Which of the following is an advantage of indexing?
Question 6A. It speeds up INSERT and UPDATE statementsB. It removes the need for a primary keyC. It allows the table to be partitioned freelyD. It reduces the total number of I/O operations needed to retrieve dataE. It stores the ROWID in every index entry
7. Which of the following is a disadvantage of indexing?
Question 7A. It decreases performance in INSERT, DELETE and UPDATE queriesB. It increases the number of I/O operations for readsC. It makes data retrieval slower for usersD. It increases tablespace by storing every row twiceE. It prevents the creation of a primary key
8. What does a database management system need on a table in order to perform indexing?
Question 8A. A foreign key to another tableB. At least one partitionC. A primary key with a unique valueD. A clustered and a non-clustered index already in placeE. A column store
9. Which of the following is NOT listed among the types of index?
Question 9A. B-Tree IndexB. Bitmap IndexC. Hash IndexD. Reverse IndexE. Quadtree Index
10. Which restriction applies to an index-organised table?
Question 10A. It cannot have a primary keyB. It is not allowed to be partitionedC. It cannot be queried with SQLD. It must use a bitmap indexE. It cannot be backed up