Swap memory on Linux server

Hi, I have a Linux server with 11GB Storage and 2GB Swap memory.

I'm using Apache and MySql on the server.

Sometimes swap memory goes Out of memory and it deleted MySQL process as it consumes more memory(approx 40%). Log for this error is like this: "kernel out of memory kill process score or sacrifice child'

So, what is the minimum Swap memory required for my server to stop this kind of issue?