an effective "vectorless RAG" is to have an LLM write search queries against the documents. e.g. if you store your documents in postgres, allow the LLM to construct a regex string that will find relevant matches. If you were searching for “Martin Luther King Jr.”, it might write something like:

    SELECT id, body
    FROM docs
    WHERE body ~* E'(?x)                                     -- x = allow whitespace/comments
      (?:\\m(?:dr|rev(?:erend)?)\\.?\\M[\\s.]+)?             -- optional title: Dr., Rev., Reverend
      (                                                      -- name forms
        (?:\\mmartin\\M[\\s.]+(?:\\mluther\\M[\\s.]+)?\\mking\\M)  -- "Martin (Luther)? King"
      | (?:\\mm\\.?\\M[\\s.]+(?:\\ml\\.?\\M[\\s.]+)?\\mking\\M)     -- "M. (L.)? King" / "M L King"
      | (?:\\mmlk\\M)                                       -- "MLK"
      )
      (?:[\\s.,-]*\\m(?:jr|junior)\\M\\.?)*                  -- optional suffix(es): Jr, Jr., Junior
    ';