A Review of Research in First-Stage Retrieval

In this paper, the first-stage retrieval technology is studied from four aspects: the development background, the frontier technology, the current challenges, and the future directions. Our contributionconsists of two main parts. On the one hand, this paper reviewed some retrieval techniques proposed by researchers and drew targeted conclusions through comparative analysis. On the other hand, dif erent research directions are discussed, and the impact of the combination of dif erent techniques on first-stage retrieval is studied and compared. In this way, this survey provides a comprehensive overview of the fieldand will hopefully be used by researchers and practitioners in the first-stage retrieval domain, inspiringnew ideas and further developments.