Prepending in Memcached with PHP (Detailed Guide w/ Code Examples)

Use Case(s)

The prepend method in Memcached is typically used when there is a need to add data to the beginning of an existing item's value. This can be useful, for example, when you are logging events in an application, and want the latest event to appear first.

Code Examples

Here is a basic example of how to use the prepend method in PHP with Memcached:

$mem = new Memcached(); $mem->addServer("localhost", 11211); // Set initial value $mem->set('key', 'world'); // Prepend "Hello " before "world" $mem->prepend('key', 'Hello '); echo $mem->get('key');

In this example, we're first initializing our connection to the Memcached server with new Memcached(), and then adding a server by specifying the host and port with addServer(). We then set an initial value using the set() function, and finally prepend 'Hello ' using prepend(). The output of this code would be "Hello world".

Best Practices

  1. Make sure that the key exists before you try to prepend to it. If the key doesn't exist, the prepend operation will fail.

  2. Always handle possible failures of Memcached operations. These operations return FALSE if they fail.

Common Mistakes

A common mistake when using prepend is assuming it will create the key if it does not exist. However, prepend only modifies existing keys. If the key does not exist, the operation fails.


Q: Can I append and prepend data to a key in Memcached?

A: Yes, Memcached allows both prepend and append operations on an existing key. It's important to remember that these operations only work if the key already exists.

Q: What happens if I try to prepend data to a non-existing key?

A: The prepend operation will fail if the key does not exist in Memcached. Always ensure the key exists before trying to prepend to it.

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