Clears (sets to empty) the data for the passed key if and only if the passed version matches the currently stored version. This method results in a conflict error on version mismatch.
Deletes a key and the data associated with it. The key is removed and no longer counts against the key quota. Note that since this method is not safe in the face of concurrent modifications, it should only be used for development and testing purposes. Invoking this method in shipping code can result in data loss and data corruption.
Update the data associated with the input key if and only if the passed version matches the currently stored version. This method is safe in the face of concurrent writes. Maximum per-key size is 128KB.