# ML based ranking using Nrtsearch

DevFeed: [ML based ranking using Nrtsearch](<https://devfeed.tech/articles/ml-based-ranking-using-nrtsearch-31461.md>)

Original publisher: [Read original article](<https://engineeringblog.yelp.com/2026/09/ml-ranking-with-nrtsearch.html>)

Author: Mohammad Mohtasham (Software Engineer); Tao Yu (Software Engineer)

Published: 2026-09-16T00:00:00Z

Content type: article

Language: en

Sources: [Yelp](<https://devfeed.tech/sources/yelp.md>)

Topics: [Inference](<https://devfeed.tech/topics/inference.md>), [Scalability](<https://devfeed.tech/topics/scalability.md>), [Latency](<https://devfeed.tech/topics/latency.md>), [recommendation systems](<https://devfeed.tech/topics/recommendation-systems.md>), [Open Source](<https://devfeed.tech/topics/open-source.md>)

Tags: [bridge](<https://devfeed.tech/tags/bridge.md>), [inference](<https://devfeed.tech/tags/inference.md>), [machine-learning](<https://devfeed.tech/tags/machine-learning.md>), [overhead](<https://devfeed.tech/tags/overhead.md>), [performance](<https://devfeed.tech/tags/performance.md>), [pipeline](<https://devfeed.tech/tags/pipeline.md>), [scalability](<https://devfeed.tech/tags/scalability.md>), [service](<https://devfeed.tech/tags/service.md>)

## AI overview

Yelp's Nrtsearch Inference Plugin embeds machine-learning ranking directly in the search layer. The article explains the scoring workflow, including model configuration, feature extraction, candidate ranking, and application-specific business logic. It describes how co-locating feature storage and inference reduces network transfer, serialization overhead, and latency compared with a standalone inference service.

## Source excerpt

We've extended Nrtsearch with the Inference Plugin, which embeds ML-based ranking directly in the search layer -- eliminating the need for a standalone scoring service. We use Nrtsearch (read more information on the blog post), a Lucene-based open-source search engine built by Yelp, to power a variety of applications such as business search, reviews search, ad delivery and photo search. In this blog post, we give a high-level overview of the Machine Learning (ML) based scoring workflow in Nrtsearch. We'll show how ML models are configured and loaded, and how different applications use custom business logic to develop, test, and...