¿Cómo puedo obtener las filas INSERTADAS y ACTUALIZADAS para una operación UPSERT en postgres?

Si agrega una columna booleana actualizada a people tabla:

ALTER TABLE people ADD COLUMN updated bool DEFAULT FALSE;

entonces podría identificar las filas actualizadas configurando updated = TRUE en el DO UPDATE SET cláusula:

INSERT INTO people (SELECT * FROM people_update)
  ON CONFLICT (name,surname)
    DO UPDATE SET age = EXCLUDED.age , street = EXCLUDED.street , city = EXCLUDED.city 
        , postal = EXCLUDED.postal
        , updated = TRUE
    WHERE 
      (people.age,people.street,people.city,people.postal) IS DISTINCT FROM 
      (EXCLUDED.age,EXCLUDED.street,EXCLUDED.city,EXCLUDED.postal)
RETURNING *;

Por ejemplo,

CREATE TABLE test.people (
    name text
    , surname text
    , age float
    , street text
    , city text
    , postal int
);
CREATE UNIQUE INDEX people_idx on people (name, surname);
ALTER TABLE people ADD COLUMN updated bool;
ALTER TABLE people ADD COLUMN prior_age float;
ALTER TABLE people ADD COLUMN prior_street text;
ALTER TABLE people ADD COLUMN prior_city text;
ALTER TABLE people ADD COLUMN prior_postal int;

INSERT INTO people (name, surname, age, street, city, postal) VALUES 
('Sancho', 'Panza', 414, '1 Manchego', 'Barcelona', 01605)
, ('Oliver', 'Twist', 182, '2 Stilton', 'London', 01837)
, ('Quasi', 'Modo', 188, $$3 Rue d'Arcole$$, 'Paris' , 01831 )
;

CREATE TABLE test.people_update (
    name text
    , surname text
    , age float
    , street text
    , city text
    , postal int
);

INSERT INTO people_update (name, surname, age, street, city, postal) VALUES 
('Sancho', 'Panza', 4140, '10 Idiazabal', 'Montserrat', 16050)
, ('Quasi', 'Modo', 1880, $$30 Champs Elysée$$ , 'Paris', 18310 )
, ('Pinocchio', 'Geppetto', 1380, '40 Nerbone', 'Florence', 18810)
;

INSERT INTO people (SELECT * FROM people_update)
  ON CONFLICT (name,surname)
    DO UPDATE SET 
        updated = TRUE
        , prior_age = (CASE WHEN people.age = EXCLUDED.age THEN NULL ELSE people.age END)
        , prior_street = (CASE WHEN people.street = EXCLUDED.street THEN NULL ELSE people.street END)
        , prior_city = (CASE WHEN people.city = EXCLUDED.city THEN NULL ELSE people.city END)
        , prior_postal = (CASE WHEN people.postal = EXCLUDED.postal THEN NULL ELSE people.postal END)
        , age = EXCLUDED.age 
        , street = EXCLUDED.street 
        , city = EXCLUDED.city 
        , postal = EXCLUDED.postal
    WHERE 
      (people.age,people.street,people.city,people.postal) IS DISTINCT FROM 
      (EXCLUDED.age,EXCLUDED.street,EXCLUDED.city,EXCLUDED.postal)
RETURNING *;

rendimientos

| name       | surname  |  age | street           | city       | postal | updated | prior_age | prior_street   | prior_city | prior_postal |
|------------+----------+------+------------------+------------+--------+---------+-----------+----------------+------------+--------------|
| Sancho     | Panza    | 4140 | 10 Idiazabal     | Montserrat |  16050 | t       |       414 | 1 Manchego     | Barcelona  |         1605 |
| Quasi      | Modo     | 1880 | 30 Champs Elysée | Paris      |  18310 | t       |       188 | 3 Rue d'Arcole |            |         1831 |
| Pinocchio  | Geppetto | 1380 | 40 Nerbone       | Florence   |  18810 | f       |           |                |            |              |

El updated columna muestra el ('Sancho', 'Panza') y ('Quasi', 'Modo') las líneas se han actualizado y ('Pinocchio', 'Geppetto') es un nuevo inserto.