What is the role of indexing in databases and how do they improve query performance?

Indexes in databases are special data structures that speed up the search and retrieval of records based on certain columns. They work like pointers, allowing the database to quickly find the needed rows without scanning the entire table.

Role of indexes:

• Accelerate the execution of SELECT queries with WHERE, JOIN, ORDER BY conditions.
• Improve performance when searching and filtering data.

However, indexes occupy additional space and slow down insert, update, and delete operations, as the index also needs to be updated.

Example: if you have a users table with an Email field, and you often search for a user by Email, creating an index on this field will allow the database to quickly find the needed records instead of scanning the entire table.