Why does mysql need an index?

MySQL requires indexes because indexes can improve the query performance of the database and the efficiency of data retrieval. Its benefits are: 1. Improve query performance to reduce the number of rows that need to be scanned during database queries; 2. Accelerate sorting and Grouping to reduce time consumption; 3. Accelerate connection operations and optimize the efficiency of connection operations; 4. Improve data uniqueness and integrity; 5. Reduce disk IO and system load.

Operating system for this tutorial: Windows 10 system, MySQL 8 version, Dell G3 computer.

MySQL requires indexes because indexes can improve the query performance of the database and the efficiency of data retrieval. An index is a data structure that stores the value and corresponding physical location of a specific column (or columns), similar to a table of contents in a book. When executing a query, MySQL can use indexes to quickly locate qualified data without scanning the entire table.

The following are some benefits of indexes:

1. Improve query performance: Indexes can reduce the number of rows that need to be scanned during database queries, making it faster by directly accessing the index. Locate the data you need to speed up queries.

2. Accelerate sorting and grouping: Indexes can help speed up ORDER BY and GROUP BY operations and reduce the time consumption of sorting and grouping.

3. Accelerate connection operations: When performing connection queries, indexes can help optimize the efficiency of the connection operation and reduce the time of the connection operation.

4. Improve data uniqueness and integrity: By creating unique indexes or primary key indexes on columns, you can ensure the uniqueness and integrity of data and avoid the existence of duplicate data or invalid data.

5. Reduce disk IO and system load: By using indexes, you can effectively reduce disk IO operations and system load, and improve the overall performance of the system.

It should be noted that indexes also have some disadvantages, such as increased storage space and reduced performance of write operations. Therefore, when designing the index, it is necessary to weigh and optimize based on specific scenarios and needs, and choose an appropriate index strategy.

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