Hybrid search and scoring pipeline

Hybrid search and scoring pipeline #

Pizza runs lexical (BM25) and vector retrieval side by side and gives you explicit, composable stages to combine and re-shape scores:

graph LR B("bm25 leg") --> F("fuse
rrf / linear / disjmax") V("vector leg") --> F F --> SC("score_functions
per-document function scoring") P["a plain query,
no retrieve"] --> SC SC --> RS("rescore
second pass on the top window") RS --> H["one ranked list"]

Every stage is optional and combines with a plain query: use score_functions alone on a keyword search, or the full chain for hybrid retrieval.

Lesson 6 — Hybrid search

Lesson 6 — Hybrid search #

Most engines hide their fusion behind a magic flag. Pizza exposes the retrieval pipeline as explicit request stages — retrieve runs retrievers in parallel, fuse merges them, and two more stages re-shape scores afterwards:

retrieve  →  fuse  →  score_functions  →  rescore
(parallel    (merge    (function           (second pass
 retrievers)  the lists) scoring)            on the top window)

Every stage is optional and combines with a plain query — you can use score_functions alone on a keyword search, or the full chain for hybrid retrieval.