plpgsql for loop -> single select?

01.sql

-- Types: ticket_query, ticket_result
-- Functions: ticket_search_1, ticket_unique_sellers

drop type ticket_query cascade;
create type ticket_query as (
    cities_from text[],
    cities_to   text[],
    date_direct date,
    date_back_min date,
    date_back_max date,
    expires     timestamp(0) without time zone,
    modified    timestamp(0) without time zone,
    adults      smallint,
    children    smallint,
    infants     smallint,
    sellers_1_adult smallint[],
    limit_filter smallint
);

create type ticket_result as (
    id        uuid,
    adults    smallint,
    children  smallint,
    infants   smallint,
    seller    smallint,
    city_from char(3),
    city_to   char(3),
    date_direct date,
    date_back   date,
    cost      integer,
    expires   timestamp(0) without time zone,
    url       text,
    modified  timestamp(0) without time zone,
    seller_data bytea,
    data      bytea
);


create or replace function ticket_search_1(q ticket_query) returns setof ticket_result as $$
declare
    s text;
    suffix text;
begin
    suffix := replace(q.date_direct::text, '-', '_');

    -- for s in
    -- execute 'explain analyze select distinct on (id) q1.*
    return query execute 'select distinct on (id) q1.*
    from (
          select ticket.id, $7, $8, $9, seller,
                 ticket.city_from, ticket.city_to, ticket.date_direct, ticket.date_back, cost,
                 ticket.expires, url, modified, seller_data, route.data
          from ticket_' || suffix || ' as ticket, route_' || suffix || ' as route
          where ticket.id = route.id
            and ' || (case when array_length(q.cities_from, 1) = 1 then 'ticket.city_from = $1[1]'
                           else 'ticket.city_from = any($1)'
                      end) || '
            and ' || (case when array_length(q.cities_to, 1) = 1 then 'ticket.city_to = $2[1]'
                           else 'ticket.city_to = any($2)'
                      end) || '
            and ' || (case when q.date_back_min is null then 'ticket.date_back is null'
                           else 'ticket.date_back between $3 and $4'
                      end) || '
            and ($5 is null or ticket.expires >= $5)
            and ($6 is null or ticket.modified > $6)
            and (case when seller = any($10) then (adults = 1 and children = 0 and infants = 0)
                      else (adults = $7 and children = $8 and infants = $9)
                 end)
          order by cost
          limit $11
    ) as q1
    order by id, cost' using q.cities_from, q.cities_to, q.date_back_min, q.date_back_max, q.expires,
        q.modified, q.adults, q.children, q.infants, q.sellers_1_adult, q.limit_filter, suffix
    ;
    -- loop
    --     raise notice '%', s;
    -- end loop;
end;
$$ language 'plpgsql';


create or replace function ticket_search_2(direct_dates date[], base_query ticket_query) returns setof ticket_result as $$
declare
    d date;
    q ticket_query;
begin
    for d in (select * from unnest(direct_dates)) loop
        q = base_query;
        q.date_direct = d;
        return query select * from ticket_search_1(q);
    end loop;
end;
$$ language 'plpgsql';


create or replace function search_2(direct_dates date[], base_query query) returns setof result as $$
declare
    d date;
    q query;
begin
    for d in (select * from unnest(direct_dates)) loop
        q = base_query;
        q.date_direct = d;
        return query select * from search_1(q);
    end loop;
end;
$$ language 'plpgsql';