PostgreSQL Inheritanced Tabla siempre vuelven Fila Con El valor nulo
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23-09-2019 - |
Pregunta
Me refiero a http://www.if-not-true-then-false.com/2009/11/howto-create-postgresql-table-partitioning-part-1/
Para reproducir el problema, aquí es algunos pasos simples a seguir:
(1) crear base de datos llamada "tutorial"
(2) realizar la siguiente consulta SQL:
CREATE TABLE impressions_by_day (
advertiser_id SERIAL NOT NULL,
day DATE NOT NULL DEFAULT CURRENT_DATE,
impressions INTEGER NOT NULL,
PRIMARY KEY (advertiser_id, day)
);
CREATE OR REPLACE FUNCTION insert_table()
RETURNS void AS
$BODY$DECLARE
_impressions_by_day impressions_by_day;
BEGIN
INSERT INTO impressions_by_day(impressions ) VALUES(888) RETURNING * INTO _impressions_by_day;
RAISE NOTICE 'After insert, the returned advertiser_id is %', _impressions_by_day.advertiser_id;
END;$BODY$
LANGUAGE 'plpgsql' VOLATILE;
ALTER FUNCTION insert_table() OWNER TO postgres;
(3) crear base de datos llamada "tutorial_partition"
(4) realizar la siguiente consulta SQL:
CREATE TABLE impressions_by_day (
advertiser_id SERIAL NOT NULL,
day DATE NOT NULL DEFAULT CURRENT_DATE,
impressions INTEGER NOT NULL,
PRIMARY KEY (advertiser_id, day)
);
CREATE OR REPLACE FUNCTION insert_table()
RETURNS void AS
$BODY$DECLARE
_impressions_by_day impressions_by_day;
BEGIN
INSERT INTO impressions_by_day(impressions ) VALUES(888) RETURNING * INTO _impressions_by_day;
RAISE NOTICE 'After insert, the returned advertiser_id is %', _impressions_by_day.advertiser_id;
END;$BODY$
LANGUAGE 'plpgsql' VOLATILE;
ALTER FUNCTION insert_table() OWNER TO postgres;
CREATE TABLE impressions_by_day_y2010m1ms2 (
PRIMARY KEY (advertiser_id, day),
CHECK ( day >= DATE '2010-01-01' AND day < DATE '2010-03-01' )
) INHERITS (impressions_by_day);
CREATE INDEX impressions_by_day_y2010m1ms2_index ON impressions_by_day_y2010m1ms2 (day);
CREATE OR REPLACE FUNCTION impressions_by_day_insert_trigger()
RETURNS TRIGGER AS $$
BEGIN
IF ( NEW.day >= DATE '2010-01-01' AND NEW.day < DATE '2010-03-01' ) THEN
INSERT INTO impressions_by_day_y2010m1ms2 VALUES (NEW.*);
ELSE
RAISE EXCEPTION 'Date out of range. Something wrong with the impressions_by_day_insert_trigger() function!';
END IF;
RETURN NULL;
END;
$$
LANGUAGE plpgsql;
CREATE TRIGGER insert_impressions_by_day_trigger
BEFORE INSERT ON impressions_by_day
FOR EACH ROW EXECUTE PROCEDURE impressions_by_day_insert_trigger();
(5) Ejecutar
SELECT * FROM insert_table() on tutorial
Tenemos
AVISO: Después de inserción, el ADVERTISER_ID devuelto es 1
(6) Ejecutar
SELECT * FROM insert_table() on tutorial_partition
Tenemos
AVISO: Después de inserción, el ADVERTISER_ID devuelto es
¿Cómo es posible conseguir ADVERTISER_ID es demasiado 1, en tutorial_partition?
Solución
El gatillo está pasando NULL espalda, que indica al INSERT que ninguna acción se va a realizar. Dado que no se realiza ninguna acción, el regreso * vuelve cláusula nada. No vas a ser capaz de interceptar (y anulación) INSERT y Uso de regresar por la misma operación y conseguir algo significativo.