CirrusSearch/Presentation

The sum total of the requirements
Make the search engine not page people. Users have to like it.

Oh yeah, and it'd be nice if it were kept up to date in real time.

The traffic volume
870 million full text searches, 3.1 billion find as you type searches a month.

The solution
replace the search system that had heroically powered search for years from the ground up with one based on Elasticsearch.