The $rankFusion aggregation stage, as released in 8.1*, has been backported to 8.0.

*except for $geoNear support

Description of Linked Ticket

Summary

Backport the initial deliverables from SPM-3541 into 8.0. The goal here is to get some of the independent features from that project to market before the full project would be completed and delivered.

Motivation

We have a large number of customers interested in combining vector and lexical search who find the current syntax cumbersome and confusing. Additionally, allowing users to go further with composeable stages via this first phased deliverable will go a long way towards realizing our differentiation in the market relative to dedicated vector databases or integrated databases with vector capabilities. The longer we push out the delivery of "something" better than current state, the longer we remain undifferentiated and the more market share we lose.

For this reason, we are aggressively pursuing an early deliverable of the hybrid search feature that captures 80% most important features identified during design with a default weighted Reciprocal Rank Fusion stage, with the custom RRF and Relative Score Fusion to follow in a second deliverable.

Documentation

Product Description
Scope
Technical Design
Docs Update