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Memcached example of memory caching in php_PHP tutorial

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Memcached is a high-performance, distributed memory object caching system used to reduce database load and improve access speed in dynamic applications. Memcached was developed by Danga Interactive to improve the access speed of LiveJournal.com. LJ has thousands of dynamic page views per second and 7 million users. Memcached greatly reduces database load, better allocates resources, and provides faster access.

Memory caching memcached example in php tutorial


Memcache installation under windows:
1. Download the Windows stable version of memcache, unzip it and put it in a certain disk, such as c: memcached
2. Enter ‘c:memcachedmemcached.exe -d install

in the terminal (i.e. cmd command interface)

’ Installation
3. Then enter: ‘c:memcachedmemcached.exe -d start’ to start. note: Later

Memcached will be automatically started as a service of Windows every time you boot up. The server has been installed

Done.
4. Download http://cmy2009.ihost.tw/download, (php_memcache address) please find the corresponding

yourself

php version file
5. Add a line ‘extension=php_memcache.dll’ to c:winntphp.ini
6. Restart apache, and then check phpinfo. If there is memcache, it means the installation is successful!

Basic settings of memcached:

-p listening port
-l The IP address of the connection, the default is the local computer
-d start starts memcached service
-d restart restart memcached service
-d stop|shutdown shut down the running memcached service
-d install install memcached service
-d uninstall uninstall memcached service
-u Run as (only valid when running as root)
-m Maximum memory usage, unit MB. Default 64mb
-m Return an error when memory is exhausted instead of deleting items
-c Maximum number of simultaneous connections, default is 1024
-f block size growth factor, default is 1.25
-n minimum allocated space, key+value+flags default is 48
-h show help

memcache environment test:
Run the following php file. If there is output, it means the environment is set up successfully. Start to appreciate the charm of memcache

!

$memcache = memcache_connect('localhost', 11211);

if ($memcache) {
$memcache->set("str_key", "string to store in memcached");
$memcache->set("num_key", 123);

$object = new stdclass;
$object->attribute = 'test';
$memcache->set("obj_key", $object);

$array = array('assoc'=>123, 345, 567);
$memcache->set("arr_key", $array);

var_dump($memcache->get('str_key'));
var_dump($memcache->get('num_key'));
var_dump($memcache->get('obj_key'));
}
else {
echo "connection to memcached failed";
}
?>

Memcached is a high-performance, distributed memory object caching system used to reduce database load and improve access speed in dynamic applications.
Memcached is developed by danga interactive and is used to improve the access speed of livejournal.com. lj has thousands of dynamic page views per second and 7 million users. Memcached greatly reduces the database load, better allocates resources, and provides faster access.


Why not use a database to do this?

Regardless of what kind of database is used (ms-sql, oracle, postgres, mysql tutorial-innodb, etc..), implementing transactions (acid, atomicity, consistency, isolation, and durability) requires a lot of overhead, especially when When using hard disk, this means that queries may block. When using a database that does not contain transactions (such as mysql-myisam), the above overhead does not exist, but the read thread may be blocked by the write thread.
memcached never blocks and is very fast.

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