Were I in a situation where I want to get the attention of a waitress in a noisy restaurant, I kind of feel like calling-out: "お姉{ねえ}さん、すみませんが、ビールもう一本お願いできますか?". I think that I've seen this done in a movie, as well as seen native speakers do this in front of me (but only at a bar where everyone was pretty drunk).
However, I think I've been told that addressing a waitress, or waiter, as お姉さん, or お兄{にい}さん, is impolite. Is this correct?
Addressing a waitress as お嬢{じょう}さん is off the charts impolite, right?
Say that I am at a beer garden and want to get the attention of one of the waitresses by saying お姉さん, what would be an appropriate substitute? Is just not addressing her at all the only way?