Maybe drop

doc_infos_after_filter(Req, DocInfo, Db, Style, DDocName, FilterName) ->
    DocInfos = case Style of
    main_only ->
        [DocInfo];
    all_docs ->
        [DocInfo#doc_info{revs=[Rev]} || Rev <- DocInfo#doc_info.revs]
    end,
    {_, PosDocInfoDict, Docs1} = lists:foldl(
        fun(DI, {P, Dict, Acc}) ->
            case couch_db:open_doc(Db, DI, [deleted, conflicts]) of
            {ok, Doc} ->
                {P + 1, dict:store(P, DI, Dict), [Doc | Acc]};
            _ ->
                {P, Dict, Acc}
            end
        end,
        {1, dict:new(), []},
        DocInfos
    ),
    Docs = lists:reverse(Docs1),
    {ok, Passes} = couch_query_servers:filter_docs(
        Req, Db, DDoc, FName, Docs
    ),
    {_, Filtered} = lists:foldl(
        fun(true, {P, Acc}) ->
            {P + 1, [dict:fetch(P, PosDocInfoDict) | Acc]};
        (_, {P, Acc} ->
            {P + 1, Acc}
        end,
        {1, []},
        Passes
    ),
    lists:reverse(Filtered).