prepend operation in Memcached is used to prepend data to an existing key's value. This is commonly used when you need to add information at the beginning of the current value stored against a key. For instance, it can be used for logging or tracking systems where most recent events need to be added at the start.
Let's suppose we have a Memcached instance running and we are using the
memcached npm module in a Node.js application.
In this example, we first set a key-value pair (
'key': 'world!'). Then, we use the
prepend method to prepend the string
'Hello ' to the current value of the key. Thus, the new value of the key becomes
prependoperation only works on keys that already exist in Memcached. Make sure the key exists before trying to prepend.
prependoperation doesn't create a new key if it doesn't exist already; it might lead to confusion because no error is thrown, but the operation doesn't have any effect either.
Q: Can I prepend data to non-string values in Memcached?
A: No, Memcached only supports string values. Therefore, you can only prepend data to keys that hold string values.