SQLite FTS5

A high-performance full-text search engine built directly into SQLite for lightning-fast indexing and prefix matching.

FTS5 transforms SQLite into a robust search engine by implementing a virtual table module that handles complex text queries across massive datasets. It supports advanced features like the BM25 ranking algorithm for relevance scoring, custom tokenizers for specialized languages, and efficient prefix searches using the * operator. By leveraging shadow tables to store inverted indexes, FTS5 allows developers to execute multi-term proximity searches and boolean logic (AND, OR, NOT) with sub-millisecond latency. It is the industry standard for adding local, offline search capabilities to mobile apps and desktop software without the overhead of external services like Elasticsearch.

https://www.sqlite.org/fts5.html