What are the php caches?

1. Full page static caching:

Generate all pages into HTML static pages, When users visit, they directly access the static page without going through the parsing process of the PHP server. This method is more common in CMS systems, such as dedecms.

Implementation method: Output caching

ob_start()--打开“输出控制缓冲”;
some code --要运行的代码;
$content=ob_get_contents()--返回“输出缓冲区的内容”;
some code --使用file_put_contents()等函数将返回的数据写入HTML文件;
ob_clearn()--清空“输出缓冲区”;

2. Page partial caching:

Static cache the parts of the page that do not change frequently, and Frequently changing parts are not cached and are finally assembled together for display; this can be implemented using a method similar to ob_get_contents(), or a page fragment caching strategy such as ESI can be used to cache relatively static fragments in dynamic pages. cache. This caching method is commonly used for product pages in shopping malls.

Related recommendations: "php Getting Started Tutorial"

3. Data caching:

A way to cache data. For example, when a certain product information in the mall is requested using the product ID, data including store information, product information, etc. can be cached. At this time, these data can be cached in a PHP file, and the file name contains the product ID. To create a unique identifier; next time someone wants to view this product, first directly adjust the information in this file without querying the database; in fact, what is cached in the cache file is a php array; in the Ecmall mall system, Used this method.

4. Query caching:

Cache based on the query. Cache the data obtained from the query in a file. The next time you encounter the same query, you can directly call the data from this file without checking the database. However, the cache file name here may need to be based on the query statement. base points to create a unique identifier.

Note: The above caching methods all need to set a valid time for the cached file. During this time, the same access will first fetch the contents of the cached file, and then re-obtain the data from the database after the valid time is exceeded. , and generate a new cache file.

5. In-memory caching:

Use redis, memcached and other nosql databases to set up PHP cache. By caching query results, you can reduce the number of database visits and improve the website. response speed.

6. Apache cache module:

After apache is installed, it is not allowed to be cached. If an external cache or squid server requires web acceleration, it needs to be set in httpd.conf. Of course, the premise is that the mod_cache module must be activated when installing apache.

When installing apache: ./configure –enable-cache –enable-disk-cache –enable-mem-cache

7. PHP APC cache extension:

Use the APC extension in PHP for caching.

8. Opcode code caching:

First the PHP code is parsed into Tokens, then compiled into Opcode code, and finally the Opcode code is executed and the result is returned; therefore, for The same php file can cache its Opcode code when it is run for the first time. The next time you execute this page, you will directly find the cached Opcode code and execute the last step directly, without the need for intermediate steps. The more well-known ones are XCache, Turck MM Cache, PHP Accelerator, etc.

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