Re: How to return seto records from seof record function?

[Laurenz Albe <laurenz.albe@xxxxxxxxxxx>]

On Tue, 2025-02-25 at 17:15 +0300, Олег Самойлов wrote:
> Postgresql 17.2
> 
> How to return seto records from seof record function? I tried pg_background extension:
>  
> CREATE OR REPLACE FUNCTION public.autonomous (p_script text)
> RETURNS SETOF record
> LANGUAGE plpgsql
> VOLATILE STRICT PARALLEL UNSAFE
> AS $autonomous$
> DECLARE
> l_id integer;
> BEGIN
> l_id := pg_background_launch(p_script);
> RETURN QUERY SELECT * FROM pg_background_result(l_id) AS (r record);
> END;
> $autonomous$;
>  
> SELECT * FROM autonomous('SELECT now()') AS (a timestamptz);
>  
> SQL Error [42804]: ERROR: structure of query does not match function result type
>   Detail: Returned type record does not match expected type timestamp with time zone in column 1.
>   Where: SQL statement "SELECT * FROM pg_background_result(l_id) AS (r record)"
> PL/pgSQL function autonomous(text) line 6 at RETURN QUERY

You need to be specific:

  SELECT * FROM pg_background_result(l_id) AS (col1 integer, col2 text, ...);

I don't think there is a way to get a generic "record" as result.
And even if you could, you would still have to specify a column list
when you call autonomous().

Attempts to write functions with polymorphic return type are usually futile.

Perhaps you can return a "SETOF jsonb"...

Yours,
Laurenz Albe