I'm trying to implement something like Google suggest on a website I am building and am curious how to go about doing in on a very large dataset. Sure if you've got 1000 items you cache the items and just loop through them. But how do you go about it when you have a million items? Further, suppose that the items are not one word. Specifically, I have been really impressed by Pandora.com. For example, if you search for "wet" it brings back "Wet Sand" but it also brings back Toad The Wet Sprocket. And their autocomplete is FAST. My first idea was to group the items by the first two letters, so you would have something like:
Dictionary<string,List<string>>
where the key is the first two letters. That's OK, but what if I want to do something similar to Pandora and allow the user to see results that match the middle of the string? With my idea: Wet would never match Toad the Wet Sprocket because it would be in the "TO" bucket instead of the "WE" bucket. So then perhaps you could split the string up and "Toad the Wet Sprocket" go in the "TO", "WE" and "SP" buckets (strip out the word "THE"), but when you're talking about a million entries which may have to say a few words each possibly, that seems like you'd quickly start using up a lot of memory. Ok, that was a long question. Thoughts?