Will memcache work in this scenario?

[ge0]

I have an application which deals with real-time data. A lot a data is written and read simultaneously from a db e.g. something like a chat application. I understand the use of memcache but I am not sure if it would be best to use it in this scenario. If yes, then how can I use it? Note, I cannot use technologies like Comet, Websockets etc.Thank you for your time.