A common use case for prepending in Memcached with Java is when you want to add data to the beginning of an existing cached value without having to read it first, then edit it, and finally write it back. This can be particularly useful for applications where the record grows dynamically, like log gathering or tracking user activity history.
The following code examples depict how to prepend data into existing keys in Memcached using Java. We'll be using the
In this example, "Hello" is set as the value for the specified key. We then prepend "World " to the same key resulting in the final value: 'World Hello'. The first parameter in the prepend function is used as the CAS value, setting it to 0 means we're not using it.
prepend. If the key doesn't exist, an error might occur.
Q: Is it possible to prepend data to a memcached key with a specific expiry?
A: No, the
prepend operation doesn't affect the expiration time of the key. The expiration time is only set when you initially
add the key.
Q: What happens if I try to prepend to a key that stores non-string data? A: The results are undefined. Prepend operation treats values as strings, so trying to prepend to a non-string value can lead to unexpected results.