Cache data optimization practice in PHP programming

With the increase in website traffic, cache data optimization is not only the key to improving website performance, but also one of the necessary conditions to ensure user experience. As a major programming language, PHP also has a lot of practical experience in caching data optimization. This article will share several cache data optimization practices based on PHP programming, aiming to help readers better understand and apply caching technology.

1. Using Memcached

Memcached is a high-performance distributed memory object caching system that can effectively reduce the burden on the database. In PHP programming, you can use the Memcached extension to achieve cached data optimization. The following is a sample code for using Memcached for caching:

<?php
// 首先生成缓存KEY
$cache_key = 'article_123';

// 判断缓存中是否存在指定KEY
if (($cache_data = $memcache->get($cache_key)) === false) {
    // 如果缓存中没有数据，则从数据库中获取相应的数据并写入缓存中
    $cache_data = $db->query($select_sql);
    $memcache->set($cache_key, $cache_data, false, 3600); // 缓存1小时
}

// 在页面中使用缓存数据
foreach ($cache_data as $data) {
    // 输出数据
}

You need to pay attention to the following issues when using Memcached for caching:

1. The cached KEY must be unique and can usually be accessed using Path, ID and other information to generate KEY;
2. The cache expiration time needs to be set according to the actual situation. Generally speaking, it needs to be adjusted according to the update frequency of cached data;
3. After reading the cached data Judgment is required. If there is no corresponding data in the cache, it needs to be obtained from the database and written into the cache;

2. Use APC cache

APC cache is a kind of The way of storing cache in PHP memory space can greatly improve the response speed of the website. Unlike Memcached, APC cache is cached in the application's memory, so reads and writes are faster. The following is a sample code for using APC for caching:

<?php
// 设置缓存KEY
$cache_key = 'article_123';

// 判断缓存中是否存在指定KEY
if (($cache_data = apc_fetch($cache_key)) === false) {
    // 如果缓存中没有数据，则从数据库中获取相应的数据并写入缓存中
    $cache_data = $db->query($select_sql);
    apc_store($cache_key, $cache_data, 3600); // 缓存1小时
}

// 在页面中使用缓存数据
foreach ($cache_data as $data) {
    // 输出数据
}

You need to pay attention to the following issues when using APC caching:

1. APC caching is cached in the memory of the application. Therefore, it is necessary to master the memory usage to avoid the problem of insufficient memory;
2. If the server starts PHP in multi-process mode, you need to pay attention to the sharing of cached data among multiple processes;
3. You need to make a judgment when reading cached data. If there is no corresponding data in the cache, you need to obtain it from the database and write it into the cache;

3. Use file cache

In addition to using memory caching, file caching can also be used to optimize the performance of PHP applications. The file cache writes data to the hard disk. The disadvantage is that the read and write speed is relatively slow, but the advantage is that it can store a large amount of data. The following is a sample code for using file caching:

<?php
// 缓存文件名
$cache_file = './cache/article_123.txt';

if (file_exists($cache_file) && (time() - filemtime($cache_file)) < 3600) {
    // 如果缓存文件存在且未过期，直接读取缓存数据
    $cache_data = file_get_contents($cache_file);
} else {
    // 如果缓存文件不存在或者已过期，则从数据库中获取数据
    $cache_data = $db->query($select_sql);
    // 将数据写入缓存文件中
    file_put_contents($cache_file, $cache_data);
}

// 在页面中使用缓存数据
foreach ($cache_data as $data) {
    // 输出数据
}

You need to pay attention to the following issues when using file caching:

1. You need to master the file reading and writing speed to avoid file reading and writing. The problem of frequent waste of I/O resources;
2. The cache expiration time needs to be set according to the actual situation. Generally speaking, it needs to be adjusted according to the update frequency of cached data;
3. When reading cached data It needs to be judged when there is no corresponding data in the cache, it needs to be obtained from the database and written into the cache;

In summary, cache data optimization is one of the important means to ensure the efficient operation of the website. First, by using Memcached, APC cache and file cache, the performance of PHP applications can be significantly improved. However, when using cache, you need to pay attention to issues such as the uniqueness of the cache KEY, the cache expiration time, and the location of data storage, so as not to affect the normal operation of the website.

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