PHP Programming Practice: How to Apply Database Caching to Improve Performance

PHP, as a popular programming language, is widely used in the field of Web development. In the actual project development process, how to optimize code performance is one of the skills that PHP programmers must master. This article will combine actual cases to introduce how to apply database caching to improve the performance of PHP programs.

1. What is database caching

Database caching refers to adding a layer of cache between the application and the database server to cache the results of frequent queries into the memory, thereby improving the query speed. Reduce the load pressure on the database. Generally, the caching mechanism stores the query results in the memory in the form of a key-value pair. When the same query is requested next time, the results are obtained directly from the cache, avoiding a new query in the database.

2. Why cache is needed

Using cache can improve the response speed and concurrency of the application. In the case of high concurrency, the load pressure of database queries is very high. Each query requires multiple steps such as connecting to the database, executing SQL statements, and returning results, thus causing a bottleneck in the database. The advantage of using cache is that it can reduce the load on the database and improve the response speed and concurrency of the system.

3. Application Example

Consider a practical application scenario: the homepage of an e-commerce website needs to display the latest product information, including product name, price, pictures and other information. These product information are stored in the MySQL database. Every request for the homepage of the website needs to connect to the database, execute the SQL statement, and return the results. The whole process is time-consuming. At this time, caching can be used to improve performance.

1. Install the Redis cache server

First, you need to install the Redis cache server. Redis is a high-performance in-memory database that supports a variety of data structures, including strings, hash tables, lists, sets, ordered sets, etc. Redis is written in C language, is very fast, and can handle high concurrent requests.

2. Configuring database cache driver

In PHP, you can use a variety of cache drivers to implement database caching, such as: Memcached, Redis, etc. Here we take Redis as an example. In PHP, using Redis cache requires installing the phpredis extension library, which can be installed through PECL or source code.

After configuring Redis, you need to set up the cache driver in the PHP program:

$redis = new Redis();
$redis->connect('127.0.0.1', 6379); //Connect to the Redis server

$driver = new DoctrineCommonCacheRedisCache();
$driver->setRedis($redis); //Set the Redis cache driver

3. Use cache to query the database

After you have the cache driver, you can use the cache to query the database. Before querying, the data is read from the cache. If it exists, the result is returned directly. If it does not exist, the database query is executed, the result is stored in the cache, and the result is returned.

The Doctrine ORM framework is used here for database query:

use DoctrineORMEntityManager;

$em = EntityManager::create($conn, $config);

$cache = $em->getConfiguration()->getQueryCacheImpl();

$query = $em->createQueryBuilder()

        ->select('p')
        ->from('Product', 'p')
        ->getQuery()
        ->useQueryCache(true)  //启用查询缓存
        ->setResultCacheDriver($driver)  //设置结果缓存驱动
        ->setResultCacheLifetime(3600)  //设置缓存时间为1小时
        ->getResult();

Before querying, call setResultCacheDriver () method to set the result cache driver, and call the setResultCacheLifetime() method to set the cache time. In the query, call the useQueryCache() method to enable the query cache, so that the results can be obtained directly from the cache in the next request, avoiding the process of connecting to the database query again.

4. Summary

Using database caching can effectively improve the performance of PHP programs, reduce the load pressure on the database, and improve the response speed and concurrency of the system. In actual development, the appropriate cache driver should be selected according to the specific situation and a reasonable cache time should be set to maximize the advantages of cache.

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