Explain how Memcached should not be used?

• Memcached common misuse is to use it as a data store, and not as a cache.
• Never use Memcached as the only source of the information you need to run your application. Data should always be available through another source as well.
• Memcached is just a key or value store and cannot perform query over the data or iterate over the contents to extract information.
• Memcached does not offer any form of security either in encryption or authentication.