Or you can do a Google search with "site:" and "link:" like http://www.google.com/search?q=site%3Anews.ycombinator.com+l...
Are you saying this capability doesn't exist, but unwilling to just come out and say so because you fear I'll dislike the lack of such a feature? I'm confused about the reason for questions without answers in response to my own question.
If you want to submit something but you're not sure if it has been submitted or not the dupe filter will tell you so clearly.
If you don't want so submit something before you've read it in full then simply read it first, then submit it.
anyway, the easiest way to search any site is simply like this:
go to google.com
type:
site:news.ycombinator.com your search keywords
the space between the .com and the first keywords is crucial.
As for how to go about this, I second your suggestion of resorting to a google search. There may be some delay between prior submissions and those submissions' indexing, but in the past (some time ago) others have commented here that google seems to have a certain fondness for frequent updates of its indexing of news.ycombinator.com .
I haven't tried this site's search feature recently. Does it perform well?