Yes, well Jake tells us that when he was a cop in Chinatown he tried to keep someone he cared about from getting hurt and in the end, since it's impossible to judge what's really going on "in Chinatown", his actions ended up ensuring she WAS hurt. So in this way the film's story is a Vertigo-style recurrence of that earlier, unglimpsed plot. The cyclical nature is even more pronounced, in this light, than in many other films, but the story that's repeated is disposed of in a couple of mumbled sentences, referred to again at the end with Jake's almost inaudible last words, "As little as possible."
dcairns   posted 28.09.11

There is a cyclical nature in Chinatown, but not as obstinate as Polanski's other films. They allude to Gittes time in Chinatown in the past and one of the final lines is 'Forget it Jake, it's Chinatown.' In terms of narrative I believe 'Chinatown' is the earliest reference in Jake's character's existence. So it states the beginning of his fictional existence in Chinatown and ends his existence on screen in Chinatown. All to be told to repress it as if his life's work is a massive insignificance.
mhcase22   posted 21.09.11