Benchmarking NBoost

NBoost comes with out-of-the-box 📦 functionality to benchmark the speed and accuracy of NBoost. If you tell NBoost which documents should be returned by a query, it will calculate how much better (or worse) the model is at ranking search results than the search api.

This is made possible by sending the correct document ids with either the ?nboost= query parameter (comma delimited) or "nboost" key in the query json body (as an array).

Index the background corpus

For demonstration, we will be indexing the MS MARCO dataset. Download the necessary collection and queries tsv files from this link and extract them.

Use the nboost-index utility to send the data to your Elasticsearch:

tar -xvzf collectionandqueries.tar.gz
nboost-index --file collection.tsv --index_name ms_marco --host <Elasticsearch host>
☕ The corpus is composed of 8.8 million paragraphs, so go grab a coffee while it finishes indexing…

Start the Proxy

Start the NBoost proxy using one of the main methods:

  1. nboost --uhost <Elasticsearch host> --uport 9200
  2. docker run koursaros/nboost:latest-tf --uhost <Elasticsearch host> --uport 9200
  3. helm install --name nboost --set uhost=<Elasticsearch host> --set uport=9200 nboost/nboost

Benchmark on the test set

import requests, csv
from collections import defaultdict

with open('') as file:
    qid_map = defaultdict(list)
    for qid, _, cid, _ in csv.reader(file, delimiter='\t'):

with open('') as file:
    for qid, query in csv.reader(file, delimiter='\t'):
        cids = qid_map[qid]
                'nboost': {
                    'rerank_cids': cids,
              'q': query,

Now check out the frontend at localhost:8000/nboost!

You should find the model latency and calculated MRR for Elasticsearch vs NBoost. Here’s our output:

MRR is short for mean reciprocal rank. Even though this model was finetuned on a different dataset, it was generalizable enough to increase Elasticsearch search relevancy by 70% (0.29 / 0.17)!