First, setting vm.swappiness to 0 does not have the beneficial impact that people say it does, and yet it's religious dogma to set it that way on MySQL servers. To my knowledge there has never been a single article published that clearly demonstrates its benefit under a controlled test. The evidence of any benefit is anecdotal at best.
Second, you can easily exclude any process from being killed by the kernel's OOM killer: "echo -17 > /proc/PID/oom_adj"
Doing such with a large memory process is a sure way to cause a server to shut down and reboot when it runs out of memory. OOM killer is bad to large memory processes, but the alternative is worse.
Ideally you don't want to swap, you definitely don't want to preemptively swap, but even swapping is better than rebooting a server.
So much time is wasted by not enough swap space resulting in rebooted or hung machines. The way linux memory allocation works, it is really not a good idea to constrain swap. It is really easy to trigger the OOM killer by using up too much virtual address space. Doing a `fork/exec` from a process near your physical memory limit can easily get you over virtual memory limit with not enough swap, even though under this condition no paging would occur.
swap on and have great week.