Simple search engine (POST or URI?)

[eluser]ehicks727[/eluser]

As I was working on the actual search controller, I came across the following issue. If someone enters multiple keywords, would you search for:

1) the complete, exact search query
2) any record that has either keywords
3) any record that has all keywords

Ideally, you'd want to rank your search results in order of relevance. You'll have to define relevance yourself because that could mean...

1. The result with the most occurrence of the keyword(s)
2. The result with the most occurrence + proximity ("keyword1 keyword2" vs. "keyword1 blah blah keyword2")


Have you tried searching for an already coded search library? Do you know that you can customize a Google search just for your domain? Why re-invent the wheel?