References: 1. ElasticSearch+ BERT: https://www.elastic.co/blog/text-similarity-search-with-vectors-in-elasticsearch 2. FAISS: https://engineering.fb.com/data-infrastructure/faiss-a-library-for-efficient-similarity-search/ 3. DiskANN: https://www.microsoft.com/en-us/research/publication/diskann-fast-accurate-billion-point-nearest-neighbor-search-on-a-single-node/