Detailed summary of php caching technology_PHP tutorial

Full page static caching
That is, all pages are generated into html static pages. The static pages are directly accessed when users visit, without going through the PHP server parsing process. This method is more common in CMS systems, such as dedecms;
A more common implementation method is to use output caching:

Copy code Code As follows:

Ob_start()
******Code to be run************
$content = Ob_get_contents();
*** *Write the cached content into the html file*****
Ob_end_clean();

Partial cache of the page
This method is to cache a page in Parts that do not change frequently are statically cached, while frequently changing blocks are not cached, and are finally assembled together for display; this can be implemented using a method similar to ob_get_contents, or you can use a page fragment caching strategy such as ESI to make it useful. Caching of relatively static fragments in dynamic pages (ESI technology, please Baidu, not detailed here).

This method can be used for example, product pages in malls;

Data caching
As the name suggests, it is a way of caching data; for example, a certain page in the mall For product information, when you use the product ID to request, you will get data including store information, product information, etc. At this time, you can cache these data into a php file, and the file name contains the product ID to create a unique identifier; next Once someone wants to view this product, they 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 or the like;

This method is used in the Ecmall mall system;

Query cache
In fact, this is the same idea as data caching, which is to cache according to the query statement; the query will be The data is cached in a file. Next time when the same query is encountered, the data will be directly retrieved from this file without checking the database; however, the cache file name here may need to be based on the query statement. Create a unique identifier;
Cache based on time changes

Actually, this is not a real caching method; the caching technologies 2, 3, and 4 above generally use time change judgment; that is, you need to set a valid time for cached files. Within this valid time, the same The content of the cache file will be fetched first when accessing, but if the set cache time is exceeded, the data needs to be re-obtained from the database and the latest cache file will be generated;
For example, I set the homepage of our mall to be updated every 2 hours Once;
Cache according to content changes

This is not an independent caching technology and needs to be used in combination; that is, when the database content is modified, the cache file is updated immediately;

For example, in a shopping mall with a lot of traffic and a lot of products, the product table must be relatively large and the pressure on this table is relatively heavy; we can cache the product display page; when the merchant modifies the product information in the background When you click Save, we will update the cache file at the same time; then, when the buyer accesses this product information, he is actually accessing a static page and does not need to access the database;

I think if the product page is not cached, then every time you access a product, you have to check the database. If 100,000 people browse the product online, the server will be under great pressure;

Memory Caching
When it comes to this, the first thing you may think of is Memcached; memcached is a high-performance distributed memory cache server. The general purpose of use is to reduce the number of database accesses by caching database query results to increase the speed and scalability of dynamic web applications.

It caches the information that needs to be cached into the system memory. When the information needs to be obtained, it is fetched directly from the memory; the more commonly used method is the key-->value method;

Copy code The code is as follows:

$memcachehost = '192.168.6.191';
$memcacheport = 11211;
$memcachelife = 60;
$memcache = new Memcache;
$memcache->connect($memcachehost,$memcacheport) or die ("Could not connect");
$memcache->set( 'key','cached content');
$get = $memcache->get($key); //Get information
?>

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

php APC cache extension
Php has An APC cache extension, which is php_apc.dll under Windows. You need to load this module first, and then configure it in php.ini:
[apc]
extension=php_apc.dll
apc.rfc1867 = on
upload_max_filesize = 100M
post_max_size = 100M
apc.max_file_size = 200M
upload_max _filesize = 1000M
post_max_size = 1000M
max_execution_time = 600; The maximum time value for each PHP page to run (seconds ), the default is 30 seconds
max_input_time = 600; The maximum time required for each PHP page to receive data, the default is 60
memory_limit = 128M; The maximum memory consumed by each PHP page, the default is 8M
Opcode Cache
We know that the execution process of php can be shown in the following figure:

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, its Opcode code can be cached the first time it is run, and the Opcode code can be executed next time When viewing the page, it will directly find the opcode code in the cache 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.

http://www.bkjia.com/PHPjc/328140.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/328140.htmlTechArticleFull page static caching is to generate html static pages for all pages, and the static pages are directly accessed when users visit. Instead of going through the php server parsing process. In this way,...