create table warriors (
  id serial primary key,
  name varchar,
  weapons varchar[]
);
insert into warriors ( name, weapons )
values
  ( 'peter', array['knife', 'sword'] ),
  ( 'george', array['gun', 'machine gun']);

select warriors as warrior from warriors;
              warrior
------------------------------------
 ( 1 ,peter,"{knife,sword}")
 ( 2 ,george,"{gun,""machine gun""}")
( 2  rows)

drop type id_sum cascade;
create type id_sum as (
  ids int4[],
  sums float8[]
);

drop type two_arrays cascade;
create type two_arrays as (
  one int4[],
  two int4[]
);

drop table if exists test_lua cascade;
create table test_lua (
  id serial primary key,
  name varchar,
  names varchar[],
  ints int4[],
  sums id_sum[]
);

insert into test_lua (name, names, ints, sums)
values 
  ('hi1', '{ho1_1, ho1_2}', '{1,2,3,4,5}', E'{"(\\"{2,3}\\",\\"{4,5}\\")"}'),
  ('hi2', '{ho2_1, ho2_2}', ARRAY[ 2 , 3 , 4 , 5 , 6 ], ARRAY[ROW(ARRAY[ 2 , 3 ], ARRAY[ 4 . 0 ,  5 . 0 ])::id_sum]);

create or replace function test_recordset_lua1()
returns setof id_sum
language plluacu
as $$
  local i =  1 
  coroutine.yield({ids = {i+ 1 , i+ 2 }, sums={i+  0 . 4 , i+ 0 . 6 } })
  i = i +  1 
  spi.return_next({ids = {i+ 1 , i+ 2 }, sums={i+  0 . 4 , i+ 0 . 6 } })
  i = i +  1 
  return ipairs{
    {ids = {i+ 1 , i+ 2 }, sums={i+  0 . 4 , i+ 0 . 6 } },
    {ids = {i+ 6 , i+ 6 }, sums={i+  0 . 5 , i+ 0 . 7 } }
    }
$$; 

select t.ids, t.sums from test_recordset_lua1() as t;
  ids  |   sums    
-------+-----------
 { 2 , 3 } | { 1 . 4 , 1 . 6 }
 { 3 , 4 } | { 2 . 4 , 2 . 6 }
 { 4 , 5 } | { 3 . 4 , 3 . 6 }
 { 9 , 9 } | { 3 . 5 , 3 . 7 }
( 4  rows)

create or replace function test_recordset_lua2()
returns setof id_sum
language plluacu
as $$--[==[prepare
  local insert = table.insert
  local function add_arr(ar, i)
      insert(ar, {ids = {i+ 1 , i+ 2 }, sums={i+  0 . 4 , i+ 0 . 6 } })
  end
--]==]
  local i =  1 
  local ar = {}
  add_arr(ar, i)
  i = i +  1 
  add_arr(ar, i)
  spi.return_next( ipairs(ar) )
  spi.return_next( set(ar) )
  ar = {}
  i = i +  1 
  add_arr(ar, i)
  i = i +  1 
  add_arr(ar, i)
  return set(ar)
$$; 

select t.ids, t.sums from test_recordset_lua2() as t;
CREATE FUNCTION
  ids  |   sums    
-------+-----------
 { 2 , 3 } | { 1 . 4 , 1 . 6 }
 { 3 , 4 } | { 2 . 4 , 2 . 6 }
 { 2 , 3 } | { 1 . 4 , 1 . 6 }
 { 3 , 4 } | { 2 . 4 , 2 . 6 }
 { 4 , 5 } | { 3 . 4 , 3 . 6 }
 { 5 , 6 } | { 4 . 4 , 4 . 6 }
( 6  rows)

create or replace function test_spi_lua2()
returns setof varchar
language plluacu
as $$--[==[prepare
local yield = coroutine.yield
--]==]
  local ret = spi.execute('select * from test_lua')
  yield( #ret )
  for i, row in ipairs(ret) do
    yield("--- by position --")
    for k,v in ipairs(row) do
      yield( ("%s: %s"):format(k, tostring(v)))
    end
    yield("--- by name --")
    for k,v in spi.tuple_by_name(row) do
      yield( ("%s: %s"):format(k, tostring(v)))
    end
  end
$$;

select * from test_spi_lua2();
      test_spi_lua2      
-------------------------
  2 
 --- by position --
  1 :  2 
  2 : hi2
  3 : table: 0x845b2a8
  4 : table: 0x845b130
  5 : table: 0x845b198
 --- by name --
 name: hi2
 id:  2 
 sums: table: 0x845b198
 ints: table: 0x845b130
 names: table: 0x845b2a8
 --- by position --
  1 :  1 
  2 : hi1
  3 : table: 0x848f6e8
  4 : table: 0x848f770
  5 : table: 0x848f7d8
 --- by name --
 name: hi1
 id:  1 
 sums: table: 0x848f7d8
 ints: table: 0x848f770
 names: table: 0x848f6e8
( 25  rows)

create or replace function test_spi_lua3(i int)
returns setof test_lua
language plluacu
as $$
  local ret = spi.query('select test_lua.* from test_lua')
  return ret
$$;

select * from test_spi_lua3( 1 );
CREATE FUNCTION
 id | name |     names     |    ints     |         sums          
----+------+---------------+-------------+-----------------------
   2  | hi2  | {ho2_1,ho2_2} | { 2 , 3 , 4 , 5 , 6 } | ("{1,2}","{3.4,5.6}")
   1  | hi1  | {ho1_1,ho1_2} | { 1 , 2 , 3 , 4 , 5 } | ("{2,3}","{4.5,5.6}")
( 2  rows)