Do I need to ground a pendant light?

I am hanging a pendant on SVT wire. The socket does not have a grounding terminal, so I bought 2 conductor wire thinking that it would work like a table lamp and not need an equipment ground. Before I commit to hanging it, I'd like to know why some light fixtures need a ground, but lamps do not. Also, do I need to buy new wire and find some clever way to ground the socket.

Thanks

Mark