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This article introduces the relevant knowledge of "A brief introduction to PHP caching technology". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

The application of php cache technology is quite common, and some people may not know much about it. Let's introduce the relevant application skills of PHP cache technology in detail.

In most cases, our website will use the database as the container for the site data storage. When you execute a SQL query, the typical process is: connect to the database-> prepare the SQL query-> send the query to the database-> get the database return results-> close the database connection. But some data in the database is completely static or does not change very often, the cache system will cache the results of the SQL query to a faster storage system, thus avoiding frequent operation of the database and greatly improve the program execution time, and caching the query results also allows you to post-process.

1. Data caching of PHP caching technology:

The data cache here refers to the database query cache. Every time you visit the page, you will first detect whether the corresponding cached data exists. If it does not exist, connect to the database, get the data, and serialize the query results and save them to a file.

Later, the same query results are obtained directly from the cache file.

Second, page caching of PHP caching technology:

Every time you visit a page, you will first check whether the corresponding cache page file exists. If it does not exist, connect to the database, get the data, display the page, and generate the cache page file at the same time, so that the page file will work the next time you visit it. (template engines and some cache classes common on the Internet usually have this feature)

3. Memory caching of PHP caching technology:

I will not introduce it here, which is not discussed in this article. I will just briefly mention:

Memcached is a high-performance, distributed in-memory object cache system, which is used to reduce database load and improve access speed in dynamic applications.

Dbcached is a distributed key-value database memory caching system based on Memcached and NMDB.

Although the above caching technology can solve the problem of frequently querying the database, its disadvantage is that the data is not timely. Here are the methods I often use in the project:

4. The time of PHP caching technology triggers caching:

Check whether the file exists and the timestamp is less than the set expiration time. If the timestamp modified by the file is larger than the current timestamp minus the expiration timestamp, then the cache is used, otherwise the cache is updated.

Do not judge whether the data should be updated within the set time, and update the cache after the set time. The above is only suitable for use when the timeliness requirement is not high, otherwise please see below.

Fifth, the content of PHP caching technology triggers caching:

Forces the cache to be updated when data is inserted or updated.

Here we can see that * involves disk read and write operations when a large amount of data needs to be updated frequently. How to solve it? In my daily projects, I usually don't cache all the content, but cache some of the content that doesn't change very often. However, in the case of heavy load, * use shared memory as the caching system.

PHP caching may have some solution here, but its disadvantage is that because each request still has to be parsed by PHP, the efficiency problem is still serious under heavy load, in which case static caching may be used.

Static caching of PHP caching technology

The static cache here refers to the HTML cache. Generally, the HTML cache does not need to determine whether the data needs to be updated, because it is usually a page that does not change the content frequently when using HTML. When the data is updated, the HTML is also forced to be updated.

This is the end of "A brief introduction to PHP caching Technology". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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