Index (database)

Welcome to the eighth episode of the Databases course! Building upon our previous discussions on databases, relational databases, SQL, NoSQL, data models, normalization, and transactions, this episode explores database indexes. We'll define what an index is, how it works, and why it's crucial for optimizing database performance, especially for read-heavy workloads. The episode will cover different types of indexes (B-tree, hash, etc.), their advantages and disadvantages, and the trade-offs involved in using them. We'll provide practical guidelines for choosing which columns to index and discuss the potential downsides of over-indexing. This knowledge will provide a bridge between single node databases, and upcoming topics like distributed databases and big data.

Check your understanding

These are the same multiple-choice questions you will see in the Quiz section after you listen to the episode. Use them here to preview or review the answers.

What is the primary purpose of a database index?

  1. To improve the speed of data retrieval operations.
  2. To reduce the storage space required by the database.
  3. To improve the security of the database.
  4. To simplify the database schema.
  5. To normalize the database.
  6. To back up the database.

What is the most common type of database index?

  1. Hash index
  2. Bitmap index
  3. B-tree index
  4. Full-text index
  5. Spatial index
  6. Linear Index

What are some potential downsides of using indexes?

  1. Increased storage space requirements.
  2. Overhead for index maintenance during write operations.
  3. Potential for slower queries in some cases.
  4. Improved read operations.
  5. All of options 1, 2 and 3.
  6. None of the above.

Which columns are good candidates for indexing?

  1. Columns frequently used in WHERE clauses.
  2. Primary key columns.
  3. Foreign key columns.
  4. Columns rarely used in queries.
  5. All of options 1, 2 and 3.
  6. Columns with very few distinct values.

What happens if a table does not have an index and a query is executed?

  1. The query will always be faster.
  2. The database will perform a full table scan.
  3. The database will automatically create an index.
  4. The query will fail.
  5. The database will use a hash function.
  6. The database will use a B-Tree.

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