Building a Semantic Search Engine


Most production information retrieval systems are built on top of Lucene which use tf-idf and BM25.

Current state of the art techniques utilize embeddings for retrieval. This workshop aims to demystify what is involved in building such a system.

This tutorial is broken into four sections :

1) Intro
- Search retrieval concepts: approaches, evaluation metrics etc.
- Overview of common production retrieval stack
- Environment Setup (10 mins)
- Walk over the notebooks and environment setup

2) Non deep learning based retrieval
- Overview of tf-idf and BM-25
- How production systems use ElasticSearch / SOLR
- Hands-on lab experience:
-- Indexing some documents with PySolr
-- Reviewing Retrieval Results from tf-idf

3) Embeddings and Vector Similarity Overview (60 min)
- Brief review of common embedding techniques: word2vec, BERT
- Briefly talk about how to train own custom embeddings
- Vector Similarity and Evaluation metrics
- Hands-on lab experience:
-- Use a pre-trained BERT embedding from HuggingFace transformers library
-- Compare results of Non deep learning and Vector Similarity

4) Serving Vector Similarity using Approximate Nearest Neighbors
- Why Vector Similarity needs ANN
- Review common Approximate Nearest Neighbors techniques in FAISS
- Overview of managed services: VertexAI, Pinecone, Milvus
- Hands-on lab experience:
-- Building FAISS Index
-- Load Index into Milvus
-- Compare Recall vs latency tradeoff

By the end of the session, a user will be able to build a production information retrieval system leveraging Embeddings and Vector Similarity using ANN.
This will allow users to utilize state of the art technologies / techniques on top of the traditional information retrieval systems.


Vishal Rathi is a Software Engineer at Walmart where he works on Walmart's E-commerce Search Engine. He received his Masters in Computer Science with a concentration in Machine Learning from Georgia Institute of Technology.

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