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phpmemcachedreliability

Force memcached to write to all servers in pool

I have thought a bit on how to make sure that a particular key is distributed to ALL memcached servers in a pool.

My current, untested solution is to make another instance of memcached, something like this:

$cluster[] = array('host' => '192.168.1.1', 'port' => '11211', 'weight' => 50);

$this->tempMemcached = new Memcached;
$this->tempMemcached->addServers($cluster);

foreach ($this->cluster() as $cluster) {    

    $this->tempMemcached->setByKey($cluster, $key, $value, $this->compress, $expireTime);

}

$this->tempMemcache->close();

What is common sense to do in this case, when certain keys need to be stored on ALL servers for reliability?

Solution

  • I think you are not using memcached the way it was designed for. Have a look at the FAQ: you should only store a single copy of your item, which, according to the hashing algorithm used, would put your item on a certain node.

    Now if you want to have an item available in all of the nodes, the only way to do this is by iterating, exactly as you are doing at the moment.

    I hope your code does handle the cases when this item isn't found in the cache.