Exploration ·
Follow a query from the box you type it into to the ten blue links: how text becomes terms, how an inverted index stores and compresses them, how BM25 scores a match, how we know a ranking is any good, and how the whole thing is split across thousands of machines — with the tools running live between the paragraphs.
Tool ·
Inside an inverted index: build one from documents and look at docIDs, frequencies and positions; compress the postings with VByte, Elias γ/δ, Golomb/Rice, Simple-9/16, FOR and PForDelta blocks of 128, Lucene's PForUtil and Roaring bitmaps (bits per posting, bit by bit); intersect with skips and galloping; and step through MaxScore, WAND and Block-Max WAND against exhaustive BM25.