memcached php memcached client memcached

The official homepage of memcache: http://pecl.php.net/package/memcache
The official homepage of memcached: http://pecl.php.net/package/memcached
The following is a record of my process of installing the Memcached version of the PHP module :
wget http://download.tangent.org/libmemcached-0.48.tar.gz
tar zxf libmemcached-0.48.tar.gz
cd libmemcached-0.48
./configure --prefix=/usr/local/libmemcached - -with-memcached
make
make install
wget http://pecl.php.net/get/memcached-1.0.2.tgz
tar zxf memcached-1.0.2.tgz
cd memcached-1.0.2
/usr /local/webserver/php/bin/phpize
./configure --enable-memcached --with-php-c/local/webserver/php/bin/php-config --with-libmemcached-dir=/usr/local /libmemcached
make
make install
Add
extension=memcached.so to php.ini
Complete
Another:
When installing libmemcached, if you only use ./configure, you may be prompted:
checking for memcached… no
configure : error: “could not find memcached binary”
The two are almost identical in use.

Copy the code The code is as follows:

$mem = new Memcache;
$mem->addServer($memcachehost, '11211');
$mem->addServer($memcachehost, '11212' ; md = new Memcached;
$servers = array(
array($memcachehost, '11211'),
array($memcachehost, '11212')

);
$md->addServers($servers);

$md ->set('hx','9enjoy'); echo $md->get('hx'); memcached has many more methods than memcache, such as getMulti, getByKey, addServers, etc.

memcached does not have the connect method of memcache, and it does not currently support long connections.

memcached supports Binary Protocol, but memcache does not, which means memcached will have higher performance.
Memcache is implemented natively and supports the coexistence of both OO and non-OO interfaces. memcached uses libmemcached and only supports OO interfaces.
More detailed differences: http://code.google.com/p/memcached/wiki/PHPClientComparison
The memcached server is a centralized caching system, and the distributed implementation method is determined by the client.
Memcached’s distribution algorithm generally has two options:
1. According to the result of hash(key), the remainder of the modular connection number determines which node is stored, that is, hash(key)% sessions.size(). This algorithm is simple and fast ,good performance. However, this algorithm has a shortcoming, that is, when memcached nodes are added or deleted, the original cached data will become invalid on a large scale, and the hit rate will be greatly affected. If there are many nodes and cached data, the cost of rebuilding the cache will be too high, so With the second algorithm.
2. Consistent Hashing, consistent hashing algorithm, its node search process is as follows:
First find the hash value of the memcached server (node), and configure it on the circle (continuum) from 0 to 232. Then use the same method to find the hash value of the key storing the data and map it to the circle. It then searches clockwise starting from the location where the data is mapped, and saves the data to the first server found. If the server is still not found after exceeding 2 to the power of 32, it will be saved to the first memcached server.
memcache uses the first method without any configuration. To implement the first method, memcached seems to use (unconfirmed):
$md->setOption(Memcached::OPT_HASH, Memcached::HASH_CRC);

The second consistent hashing algorithm:
memcache in php. ini add



Copy code

The code is as follows:


Memcache.hash_strategy =consistent
Memcache.hash_function =crc32


memcached is added to the program (not confirmed)

Copy code The code is as follows :

$md->setOption(Memcached::OPT_DISTRIBUTION, Memcached::DISTRIBUTION_CONSISTENT);
$md->setOption(Memcached::OPT_HASH, Memcached::HASH_CRC);
or

$mem->setOption (Memcached::OPT_DISTRIBUTION,Memcached::DISTRIBUTION_CONSISTENT);
$mem->setOption(Memcached::OPT_LIBKETAMA_COMPATIBLE,true);

Some reference documents:
memcached distribution test report (hash function selection in the case of consistent hashing):
http://www.iteye.com/topic/346682
The difference between php module memcache and memcached: http:// www.jb51.net/article/27366.htm
PHP module: Memcached > Memcache: http://www.jb51.net/article/27367.htm
20110509@@UPDATE:
If you install libmemcached, there will be the following error message:
make[2]: *** [clients/ms_conn.o] Error 1
make[2]: Leaving directory `/www/soft/libmemcached-0.48'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/www/soft/libmemcached-0.48'
make: *** [all] Error 2
Can be added when configure --disable-64bit CFLAGS="-O3 -march= i686"
That is: ./configure --prefix=/usr/local/libmemcached --with-memcached --disable-64bit CFLAGS="-O3 -march=i686"

The above introduces memcached, the memcached client of Memcached php, including Memcached content. I hope it will be helpful to friends who are interested in PHP tutorials.