Postgres run multithreaded call from function-CodePudding

I need to run one stored function from another in PostgreSQL server, but I need to run inner function in 4 threads to reduce in execution time. I can do that by make 4 threaded calls from backend, but it will more complex than call inside PostgeSQL server. I'm using plpgsql language.

I'd like to make something like following

create or replace function abc(some_data integer)
returns integer
language plpgsql
as $$
declare
  intermediate_data some_my_type;
  is_done boolean;
  result integer;
begin
  intermediate_data := result_of_synchronous_call(some_data);

  async perform asinchronous_call(intermediate_data.part1);
  async perform asinchronous_call(intermediate_data.part2);
  async perform asinchronous_call(intermediate_data.part3);
  async perform asinchronous_call(intermediate_data.part4);

  SELECT count(*) = 4 INTO is_done FROM results;
  while not is_done loop
    SELECT pg_sleep(10);
    SELECT count(*) = 4 INTO is_done FROM results;
  end loop;
  
  SELECT sum(result_field) INTO result FROM results;
  return result;
end;
$$

CodePudding user response：

There is no pretty way to do this. The best I can think of is to use the dblink extension and use dblink_send_query to send a query. Completion status can be checked with dblink_is_busy, and the results are ultimately collected with dblink_get_result.