Release History & API Evolution

Version changelog and SQL schema evolution of VectorChord-BM25 (vchord_bm25) from v0.1.0 to v0.3.0 and main.

This page tracks the release history and SQL schema evolution of vchord_bm25 (pgsty/vchord_bm25 / supervc-stack/VectorChord-bm25).

Version Summary Matrix

Version	Schema	Indexed Type	Tokenizer	Key Additions
`main` (Next-Gen)	Extension schema	`tsvector`	Native `to_tsvector` (or custom)	Complete storage & index engine rewrite on native `tsvector`; external sort parallel `ambuild`; index reloptions (`options`, `limit`, `prefilter`); `bm25.*` GUCs; PostgreSQL 18 support.
`v0.3.0`	`bm25_catalog`	`bm25vector`	`pg_tokenizer`	Added `bm25_page_inspect(regclass, int)`, `to_bm25query(regclass, int[])` overload, and PostgreSQL 18 compatibility.
`v0.2.2`	`bm25_catalog`	`bm25vector`	`pg_tokenizer`	Added `bm25_catalog.enable_prefilter` GUC for accurate filtered Top-K BM25 search with `WHERE` clauses.
`v0.2.1`	`bm25_catalog`	`bm25vector`	`pg_tokenizer`	Bug fixes for growing/sealed segment transitions and vacuum cleanup.
`v0.2.0`	`bm25_catalog`	`bm25vector`	`pg_tokenizer`	Added `=` and `<>` equality operators on `bm25vector` and implicit cast `CREATE CAST (int[] AS bm25vector) AS IMPLICIT`.
`v0.1.1`	`bm25_catalog`	`bm25vector`	`pg_tokenizer`	Decoupled tokenization into standalone `pg_tokenizer` extension; changed `to_bm25query(regclass, bm25vector)` signature.
`v0.1.0`	`bm25_catalog`	`bm25vector`	Built-in `unicode`	Initial release with `bm25vector`, `bm25query`, `USING bm25`, and Block-WeakAnd Top-K scan.

Added page diagnostic function:

CREATE FUNCTION bm25_page_inspect(index regclass, blkno INT) RETURNS TEXT;

Added to_bm25query(regclass, int[]) convenience overload in main/late 0.3.x.

Added prefiltering support in Block-WeakAnd (bm25_catalog.enable_prefilter GUC, enabled by default in 0.3.0).
Improved MVCC visibility checking during index scans to prevent dead/filtered tuples from polluting the Top-K threshold.

Added = and <> operators for bm25vector.
Added implicit cast from int[] to bm25vector (_vchord_bm25_cast_array_to_bm25vector), allowing tokenize(text, name) output (INT[]) to be assigned or passed directly wherever bm25vector is expected.

Extracted built-in create_tokenizer / tokenize functions into the dedicated pg_tokenizer extension (tokenizer_catalog), enabling rich text analyzers, Snowball stemmers, stopwords, synonyms, HuggingFace models, jieba, and lindera.
Simplified to_bm25query(index_oid regclass, query_vector bm25vector) to accept a bm25vector directly.

Replaced custom bm25vector with PostgreSQL’s native tsvector (CREATE OPERATOR CLASS bm25_ops FOR TYPE tsvector USING bm25), allowing users to index to_tsvector(...) columns directly with USING bm25.
Added parallel index build (bm25_parallel_build_main) with external merge sort and constant maintenance memory consumption.
Added configurable BM25 hyperparameters ( $k_1 \in [1.2, 2.0]$ , $b \in [0.0, 1.0]$ ) via WITH (options = $$ k1 = 1.2, b = 0.75 $$).