Show HN: Postgres extension for BM25 relevance-ranked full-text search

Modern ranked text search for Postgres.

• Simple syntax: ORDER BY content <@> 'search terms'
• BM25 ranking with configurable parameters (k1, b)
• Works with Postgres text search configurations (english, french, german, etc.)
• Fast top-k queries via Block-Max WAND optimization
• Parallel index builds for large tables
• Supports partitioned tables
• Best in class performance and scalability

Status: v1.0.0 - Production ready. pg_textsearch supports PostgreSQL 17 and 18.

Installation involves cloning the repository, running make install, and adding pg_textsearch to shared_preload_libraries in postgresql.conf.

Usage example:

CREATE INDEX docs_idx ON documents USING bm25(content) WITH (text_config='english');
SELECT * FROM documents ORDER BY content <@> 'database system' LIMIT 5;

The extension supports both pre-filtering and post-filtering strategies, similar to pgvector. For large datasets, it offers parallel index builds and a bm25_force_merge function to consolidate index segments for better query performance.