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How does database indexing speed up query performance?
Asked on Oct 31, 2025
Answer
Database indexing significantly enhances query performance by allowing the database engine to locate and retrieve data more efficiently. Instead of scanning every row in a table, an index provides a quick lookup capability, similar to a book's index, which drastically reduces the amount of data the database needs to process.
Example Concept: An index in a database is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space. Indexes are created on columns that are frequently used in WHERE clauses, JOIN conditions, or as part of an ORDER BY clause. By maintaining a sorted order of the indexed columns, the database can quickly narrow down the search space, resulting in faster query execution times.
Additional Comment:
- Indexes can be created on one or more columns, known as composite indexes.
- While indexes speed up read operations, they can slow down write operations due to the overhead of maintaining the index.
- Common types of indexes include B-tree, hash, and full-text indexes, each suited for different query types.
- Proper indexing strategy is crucial for optimizing database performance, especially in large-scale applications.
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