Reference

Data Types

• bm25vector: A specialized vector type for storing BM25 tokenized text. Structured as a sparse vector, it stores token IDs and their corresponding frequencies. For example, {1:2, 2:1} indicates that token ID 1 appears twice and token ID 2 appears once in the document.
• bm25query: A query type for BM25 ranking.

Functions

• to_bm25query(index_name regclass, query_vector bm25vector) RETURNS bm25query: Convert the input text into a BM25 query.

Operators

• bm25vector = bm25vector RETURNS boolean: Check if two BM25 vectors are equal.
• bm25vector <> bm25vector RETURNS boolean: Check if two BM25 vectors are not equal.
• bm25vector <&> bm25query RETURNS float4: Calculate the negative BM25 score between the BM25 vector and query. The lower the score, the more relevant the document is. (This is intentionally designed to be negative for easier sorting.)

Casts

• int[]::bm25vector (implicit): Cast an integer array to a BM25 vector. The integer array represents token IDs, and the cast aggregates duplicates into frequencies, ignoring token order. For example, {1, 2, 1} will be cast to {1:2, 2:1} (token ID 1 appears twice, token ID 2 appears once).

GUCs

• bm25_catalog.bm25_limit (integer): The maximum number of documents to return in a search. Default is 100, minimum is -1, and maximum is 65535. When set to -1, it will perform brute force search and return all documents with scores greater than 0.
• bm25_catalog.enable_index (boolean): Whether to enable the bm25 index. Default is true.
• bm25_catalog.segment_growing_max_page_size (integer): The maximum page count of the growing segment. When the size of the growing segment exceeds this value, the segment will be sealed into a read-only segment. Default is 4,096, minimum is 1, and maximum is 1,000,000.