Search engines

How does text become fast, ranked retrieval?

Go inside tokenization, inverted indexes, scoring, segments, merges, shards, and near-real-time indexing.

Systems compared

• Lucene
• Elasticsearch
• OpenSearch
• Solr

Open the engine

1. Analysis and tokenization
2. Inverted indexes
3. BM25 scoring
4. Segments and merges
5. Shards and replicas

Reconstruction lab

Construct a tiny inverted index, rank results, and diagnose a mapping or shard design mistake.