Database query cache optimization practice in PHP programming

In PHP programming, database query is an essential part, and query performance is the key optimization point. One direction in optimization is to cache query results to avoid repeated queries. This article will introduce practical methods for database query cache optimization.

1. Caching Principle

Caching query results is based on the principle of data immutability, that is, the same query results will not change before the data changes. Therefore, a query only needs to be executed once, and subsequent queries can be read from the cache. The implementation of caching is to store query results in memory and then query them by caching key-value pairs. In the implementation of cache, the time, capacity and cache update mechanism of cache storage need to be considered.

2. Cache implementation

1. Memcached

Memcached is a common cache storage method that can be used in a variety of programming languages ​​and web servers. The advantages are extreme speed and scalability. In PHP, caching of query results can be easily implemented through the Memcached extension. The following is a simple example code:

$cache = new Memcached();
$cache->addServer('localhost', 11211);

$key = md5('SELECT * FROM `table`');
$result = $cache->get($key);

if ($result === false) {
    $result = // 执行查询操作
    $cache->set($key, $result, 3600); // 缓存有效期1小时
}

// 使用查询结果

2. Redis

Redis is another common A cache storage method with more data structures and functions, such as storage structures, transactions and persistence. In PHP, you can easily cache query results through Redis extension. The following is a simple example code:

$redis = new Redis();
$redis->connect('localhost', 6379);

$key = md5('SELECT * FROM `table`');
$result = $redis->get($key);

if ($result === false) {
    $result = // 执行查询操作
    $redis->set($key, $result);
    $redis->expire($key, 3600); // 缓存有效期1小时
}

// 使用查询结果

3. Caching practice

1. Only cache frequent query results

For results with fewer queries, caching may waste memory space. You can determine whether the query results are worth caching by setting a query threshold. For example, for a certain query result, if the number of queries exceeds 100 times within a period of time, it will be cached.

2. Timeout update cache

Even if the data does not change, the query results may need to be updated because the cache time is too long. The cache expiration time can be set to a suitable interval, such as one hour. When the cache reaches the expiration time and is queried again, the cache will be automatically updated.

3. Update cache manually

In some cases, the cache update process may be time-consuming, such as data update or deletion operations. In this case, you can use the manual cache update method, that is, clear the cache directly when the data is updated or deleted. This ensures the real-time nature of the cache.

4. Summary

In PHP programming, the optimization of database query cache is a very important part. By caching query results, query performance and server response speed can be greatly improved while avoiding repeated queries. In practice, different cache implementation methods and optimization technologies can be used according to actual conditions to achieve the best performance optimization effect.

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