The difference between mysql indexes

MySQL index (Index) is an effective method to improve query speed. When creating a table, you can improve the retrieval speed of SELECT by specifying an index and find the desired data rows faster. Common classifications of MySQL indexes include: ordinary indexes, unique indexes, primary key indexes, full-text indexes, etc. Each index type has different advantages and disadvantages. Correct and reasonable selection of indexes and optimization of indexes are critical to improving data query efficiency. In this article, we will cover the differences between MySQL indexes and their optimization.

1. Ordinary index

Ordinary index is the most basic index type and does not contain any constraints or restrictions. Indexes are created solely to increase query speed. When we search using the WHERE clause, MySQL uses a normal index to locate rows that meet the criteria. If the query conditions use index fields, MySQL can locate the required data more quickly. Ordinary indexes can be created on various basic data types such as character, numeric, and date types. Example of establishing a normal index:

CREATE INDEX idx_name ON player(name);

2. Unique index

The unique index is the same as the normal index, and is also an index established to improve query speed. A unique index does not allow duplicate values ​​in its fields, so a unique index can be used on any field that must be unique. When MySQL performs INSERT and UPDATE operations, it will detect the unique index to ensure the uniqueness of its value. Example of creating a unique index:

CREATE UNIQUE INDEX idx_id ON player(id);

3. Primary key index

The primary key index is a special unique index, which has unique constraints. However, the primary key index requires that all index columns are not empty. , that is, the NOT NULL constraint is set. The primary key index is also the most commonly used index type. The primary key index can be composed of a single column or multiple columns. Example of establishing a primary key index:

CREATE TABLE player (
    id INT PRIMARY KEY, 
    name VARCHAR(50)
);

4. Full-text index

Full-text index is a special index in MySQL for text type data (such as text, character type, and even binary type data). It can help us query data faster, and is mainly used for rapid matching of text information such as articles, blogs, comments, product descriptions, etc. The full-text index supports Chinese word segmentation and can determine the appropriate position of keywords in the text to quickly locate relevant text. Example of establishing a full-text index:

CREATE FULLTEXT INDEX idx_text ON article(title, content);

The above is the difference between MySQL indexes. In practical applications, we often use multiple index types to optimize MySQL database query efficiency. Reasonable selection and optimization of indexes can significantly improve the query performance of the database, thus improving the response speed and user satisfaction of the website. Of course, improper use of indexes can also cause the performance of the MySQL database to deteriorate, so we also need to understand some optimization principles and techniques.

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