Analysis of several commonly used PHP caching mechanisms

PHP caching mechanism analysis: several commonly used methods, specific code examples are required

Abstract:
In Web development, in order to improve the performance and response of web pages For speed, we usually use caching to reduce server load and network transmission delays. As a popular server-side scripting language, PHP also provides a variety of caching mechanisms to optimize page loading speed. This article will introduce several caching methods commonly used in PHP and give specific code examples.

1. Page caching
1. Static HTML file
Static HTML file is the simplest and most common page caching method. We can use PHP to cache dynamically generated web pages as static HTML files, and then directly return this static file every time it is accessed to avoid executing PHP code again. Specific code examples are as follows:

// 检查缓存文件是否存在
if (file_exists('cache.html')) {
    // 返回缓存文件
    readfile('cache.html');
    exit;
}

// 动态生成网页内容
$content = '...';

// 将网页内容写入缓存文件
file_put_contents('cache.html', $content);

// 返回网页内容
echo $content;

2. Server-side caching
Server-side caching stores dynamically generated web pages in server memory to speed up subsequent access. PHP provides a variety of server-side caching extensions, such as APC, Redis and Memcached. The following is a sample code for page caching using APC extension:

// 检查缓存是否存在
if (apc_exists('page_cache')) {
    // 返回缓存数据
    echo apc_fetch('page_cache');
    exit;
}

// 动态生成网页内容
$content = '...';

// 将网页内容存储到缓存
apc_store('page_cache', $content);

// 返回网页内容
echo $content;

2. Data caching
1. Variable caching
Variable caching stores frequently read data in memory to reduce The number of database queries. PHP provides multiple variable caching libraries, such as Memcached and Redis. The following is a sample code for variable caching using Memcached extension:

// 连接Memcached服务器
$memcached = new Memcached();
$memcached->addServer('127.0.0.1', 11211);

// 检查缓存是否存在
if ($memcached->get('data_cache')) {
    // 返回缓存数据
    $data = $memcached->get('data_cache');
} else {
    // 从数据库中查询数据
    $data = '...';

    // 将查询结果存储到缓存
    $memcached->set('data_cache', $data, 3600); // 缓存一小时
}

// 使用数据
echo $data;

2. Database query cache
Database query cache stores frequently executed SQL statements and their query results in memory to improve the database Query efficiency. PHP's PDO extension provides SQL query caching functionality. The following is a sample code that uses PDO for query caching:

// 连接数据库
$dsn = 'mysql:host=localhost;dbname=test';
$db = new PDO($dsn, 'username', 'password');

// 开启查询缓存
$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
$db->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true);
$db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
$db->query('SET GLOBAL query_cache_size = 1000000'); // 设置缓存大小

// 执行查询语句
$sql = 'SELECT * FROM users';
$result = $db->query($sql); // 查询结果将被缓存起来

// 使用查询结果
foreach ($result as $row) {
    echo $row['name'];
}

Conclusion:
By properly using the caching mechanism, we can improve the loading speed and performance of web pages. This article introduces several caching methods commonly used in PHP and gives specific code examples. Based on actual needs and project scale, we can choose an appropriate caching method to optimize PHP applications.

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