Fast Construction and Maintenance of the HYB Index

We show that a HYB index can be constructed twice as fast as an ordinary inverted index. As shown in a series of recent works, the HYB index enables very fast prefix searches, which in turn is the basis for fast processing of many other types of advanced queries, including autocompletion, faceted search, synonym search, errortolerant search etc. HYB can be viewed as a “half-inverted index“ and one of the main reasons for our speed improvement is that for a half-inversion we can omit the expensive index merging phase required for an ordinary inverted index. The algorithm has been carefully engineered, with special attention paid to cache-efficiency and disk cost. We compared our algorithm to the state-of-the-art index construction from Zettair. We also show that our HYB index construction naturally supports very fast dynamic index updates with running time that is independent of the size of the collection.