How to query database data cache with PHP

In web development, querying database data is a common operation. For frequent query operations, if a request is made to the database every time, the pressure on the database will increase, the page response speed will slow down, and the user experience will be affected. In order to solve this problem, caching technology can be used to cache frequently queried data in the cache server, reducing the burden on the database and improving page response speed.

As a popular web development language, PHP provides a variety of caching technologies. This article will introduce the implementation method of PHP query database data caching.

1. The concept of caching technology

Cache technology is a technology that stores calculation results in high-speed memory so that they can be quickly retrieved for future use. In web applications, cache can refer to a component, a block of files, or an entire page. Commonly used caching technologies are:

1. File caching: write data into a cache file. The next time you access the data, first check whether the cache file exists. If it exists and is valid, read the cache directly. data in the file, otherwise the data is read from the database and the cache file is updated.
2. Memory caching: To cache data in memory, you can use PHP's built-in array or use extensions such as Memcached, Redis, etc.
3. Interface caching: Call other API interfaces to obtain data and cache the data.

2. Implementation methods of PHP query database data caching

The following will introduce two common implementation methods of PHP query database data caching.

1. File cache implementation

This implementation method is suitable for caching smaller data and is suitable for stand-alone environments. You can choose to use PHP's own file cache function file_get_contents() and file_put_contents() implements caching.

First, you need to determine the name and cache time of the cache file. For example, we can set the file name to cache.txt and the cache time to 10 minutes.

// 定义缓存文件名和缓存时间
$cache_file = 'cache.txt';
$cache_time = 600; // 10分钟

Then, before querying the data, check whether the cache file exists. If it exists and has not expired, read the data directly from the cache file; if it does not exist or has expired, read the data from the database. and update cache files.

// 检查缓存文件是否存在
if (file_exists($cache_file) && time() - filemtime($cache_file) < $cache_time) {
    // 缓存文件未过期，直接读取缓存文件中的数据
    $data = file_get_contents($cache_file);
} else {
    // 缓存文件不存在或已过期，从数据库中读取数据
    $data = query_data_from_database();
    // 将数据写入缓存文件中
    file_put_contents($cache_file, $data);
}

2. Memory cache implementation

This implementation method is suitable for caching larger data and is suitable for cluster environments. When implementing memory caching, you can use PHP's built-in array or use extensions such as Memcached, Redis, etc.

First, create a PHP array as a cache and store the queried data in the array.

// 创建一个PHP数组作为缓存
$cache_data = array();
// 查询数据并存储在缓存数组中
$query_result = query_data_from_database();
if (!empty($query_result)) {
    $cache_data['data'] = $query_result;
}

Then, check whether the required data exists in the cache array. If it exists, return the cached data directly; if it does not exist, get the data from the database, store it in the cache array, and return the data.

// 检查缓存数组是否存在所需的数据
if (isset($cache_data['data'])) {
    // 直接返回缓存数据
    $data = $cache_data['data'];
} else {
    // 从数据库中查询数据
    $query_result = query_data_from_database();
    // 将数据存储在缓存数组中
    if (!empty($query_result)) {
        $cache_data['data'] = $query_result;
    }
    // 返回数据
    $data = $query_result;
}

3. Summary

For frequently occurring query operations, using caching technology can reduce the burden on the database and improve page response speed. This article introduces two common implementation methods of PHP query database data caching: file caching and memory caching. File caching is suitable for caching smaller data and can be implemented using PHP's own file caching function; memory caching is suitable for caching larger data and can be implemented using PHP's built-in arrays or extensions such as Memcached and Redis. In actual development, appropriate caching technology should be selected based on actual conditions.

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