PHP and MySQL index selection and creation strategies and their impact on query performance

PHP and MySQL index selection and creation strategies and their impact on query performance

Indexes are an important tool in relational databases used to improve query performance. In PHP development, using the MySQL database is a common choice. This article will explore index selection and creation strategies in PHP and MySQL development, and analyze their impact on query performance. At the same time, specific code examples will be provided to help readers better understand these concepts.

1. The role and selection strategy of index
The index is a special data structure used to improve the query efficiency of data in the database. It connects the keywords in the data to the corresponding physical storage locations by pre-building a balanced binary tree (B-tree). In this way, the corresponding storage location can be directly located through the index during query without traversing the entire data table.

When selecting an index, you need to make a judgment based on actual needs and the characteristics of the data table. The following are some common index selection strategies:

1. Primary key index: For each data table, you should try to select a suitable primary key, and then use the primary key index. The primary key index is unique and can efficiently find and modify data records.
2. Unique index: For columns that need to ensure data uniqueness, you can create a unique index. Unique indexes can prevent the insertion of duplicate data and can also improve efficiency when querying.
3. Foreign key index: When it comes to related queries between multiple tables, you can create a foreign key index. Foreign key indexes can improve the performance of related queries and avoid full table scans.
4. Combined index: When a query statement involves multiple columns, you can consider creating a composite index. Combined indexes can store the values ​​of multiple columns through a joint index, thereby improving query efficiency.

2. Index creation strategy and sample code
The index creation strategy mainly includes selecting appropriate columns and types, avoiding too many indexes, and paying attention to the order of indexes.

1. Choose appropriate columns and types: Index columns should be selected based on query frequency and selectivity. Select columns that are frequently queried, and try to select columns with higher selectivity, that is, columns with fewer types of values, which can effectively reduce the index scope.

The following is a sample code that demonstrates how to create a primary key index in PHP:

<?php
// 连接数据库
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";

$conn = new mysqli($servername, $username, $password, $dbname);

// 创建数据表
$sql = "CREATE TABLE users (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(30) NOT NULL,
email VARCHAR(50),
reg_date TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
)";

if ($conn->query($sql) === TRUE) {
  echo "Table users created successfully";
} else {
  echo "Error creating table: " . $conn->error;
}

// 创建主键索引
$sql = "ALTER TABLE users ADD INDEX (id)";

if ($conn->query($sql) === TRUE) {
  echo "Index created successfully";
} else {
  echo "Error creating index: " . $conn->error;
}

// 关闭连接
$conn->close();
?>

2. Avoid too many indexes: Indexes will take up additional storage space. Too many indexes not only increase storage overhead, but also affect the performance of insert and update operations. Therefore, you should avoid creating too many redundant indexes.
3. Pay attention to the order of the index: For combined indexes, especially when multi-column queries are involved, the order of the index columns is also important. The most commonly used columns should be placed first to improve query performance.

In summary, the selection and creation strategies of PHP and MySQL indexes have an important impact on query performance. When selecting and creating indexes, we need to make judgments based on the actual situation and follow certain empirical principles. Through reasonable use of indexes, we can significantly improve the query performance of the database in PHP development and improve the user experience.

Reference:

• PHP Manual: https://www.php.net/manual/en/index.php
• MySQL Documentation: https:/ /dev.mysql.com/doc/

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