exemplo.sql

-- criação da função
CREATE OR REPLACE FUNCTION fnc_roda_selects()
RETURNS SETOF RECORD
AS $$
DECLARE 
	rResult RECORD;
BEGIN

 -- tenta buscar dados na tabela com um filtro especifico
 PERFORM * FROM dw.dim_tempo;

IF FOUND THEN
   FOR rResult IN
   	SELECT 
   		INTO rResult 
   		*
    FROM dw.tabela1
    -- COLOCAR FILTROS AQUI
   LOOP
   	RETURN NEXT rResult;
   END LOOP;
ELSE
   FOR rResult IN
   	SELECT 
   		INTO rResult 
   		*
    FROM dw.tabela_dois
    -- COLOCAR FILTROS AQUI
   LOOP
   	RETURN NEXT rResult;
   END LOOP;

END IF;
END;
$$ LANGUAGE 'plpgsql';

-- Exemplo de chamada
SELECT * FROM fnc_roda_selects() AS (col1 TEXT, col2 NUMERIC);