'hybrid': native fusion of dense + lexical (only distinct on backends with native fusion, e.g.
Mongo Atlas; on pgvector it degrades to dense + a legacy app-side keyword fallback).
'keyword': embedding-free lexical retrieval; the mechanism is backend-specific — native Lucene BM25
on Mongo Atlas (ranked, term-optional: a partial-term query still matches), and a boolean substring
filter on pgvector (every term must appear literally; unranked).
Retrieval mode for a knowledge-base search.
'vector': dense-only similarity.'hybrid': native fusion of dense + lexical (only distinct on backends with native fusion, e.g. Mongo Atlas; on pgvector it degrades to dense + a legacy app-side keyword fallback).'keyword': embedding-free lexical retrieval; the mechanism is backend-specific — native Lucene BM25 on Mongo Atlas (ranked, term-optional: a partial-term query still matches), and a boolean substring filter on pgvector (every term must appear literally; unranked).