Query execution time increased dramatically without type cast - postgresql

Question

The query in this state takes more than 5 minutes to execute. If I remove any of the ::DATE conversions (see comment in code) the execution time goes < 500 ms.
For example, if I change gf.created::DATE to gf.created the performance is dramatically increased. Same happens if I change gtg.created::DATE to gtg.created.
Why is there a huge difference when using both ::DATE conversions if each shows great performance on its own?
SELECT gtg6.tipo_ganado, COUNT(gtg6.tipo_ganado) animales
FROM agroapp.ganado g
INNER JOIN (SELECT gf5.ganado_id, gf5.fundo_id
FROM agroapp.ganado_fundo gf5
INNER JOIN (SELECT MAX(gf3.ganado_fundo_id) ganado_fundo_id
FROM agroapp.ganado_fundo gf3
INNER JOIN (SELECT gf.ganado_id, MAX(gf.created) created
FROM agroapp.ganado_fundo gf
WHERE gf.isactive = 'Y'
-- HERE CHANGING gf.created::DATE TO gf.created
AND gf.created::DATE <= '20181030'::DATE
GROUP BY gf.ganado_id) gf2 ON (gf2.ganado_id = gf3.ganado_id AND gf2.created = gf3.created)
WHERE gf3.isactive = 'Y'
GROUP BY gf3.ganado_id) gf4 ON gf4.ganado_fundo_id = gf5.ganado_fundo_id
) gf6 ON gf6.ganado_id = g.ganado_id
INNER JOIN (SELECT gtg5.ganado_id, gtg5.tipo_ganado
FROM agroapp.ganado_tipo_ganado gtg5
INNER JOIN (SELECT MAX(gtg3.ganado_tipo_ganado_id) ganado_tipo_ganado_id
FROM agroapp.ganado_tipo_ganado gtg3
INNER JOIN (SELECT gtg.ganado_id, MAX(gtg.created) created
FROM agroapp.ganado_tipo_ganado gtg
WHERE gtg.isactive = 'Y'
-- OR HERE CHANGING gtg.created::DATE TO gtg.created
AND gtg.created::DATE <= '20181030'::DATE
GROUP BY gtg.ganado_id) gtg2 ON (gtg2.ganado_id = gtg3.ganado_id AND gtg2.created = gtg3.created)
WHERE gtg3.isactive = 'Y'
GROUP BY gtg3.ganado_id) gtg4 ON gtg4.ganado_tipo_ganado_id = gtg5.ganado_tipo_ganado_id
) gtg6 ON gtg6.ganado_id = g.ganado_id
WHERE g.organizacion_id = 21
GROUP BY gtg6.tipo_ganado
ORDER BY gtg6.tipo_ganado;
Table definitions
All 3 tables have around 50000 rows:
CREATE TABLE agroapp.ganado_fundo
(
ganado_fundo_id serial NOT NULL,
organizacion_id integer NOT NULL,
isactive character(1) NOT NULL DEFAULT 'Y'::bpchar,
created timestamp without time zone NOT NULL DEFAULT now(),
createdby numeric(10,0) NOT NULL,
updated timestamp without time zone NOT NULL DEFAULT now(),
updatedby numeric(10,0) NOT NULL,
fundo_id integer NOT NULL,
ganado_id integer NOT NULL,
CONSTRAINT ganado_fundo_pk PRIMARY KEY (ganado_fundo_id),
CONSTRAINT ganado_fk FOREIGN KEY (ganado_id)
REFERENCES agroapp.ganado (ganado_id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION
)
CREATE TABLE agroapp.ganado_tipo_ganado
(
ganado_tipo_ganado_id serial NOT NULL,
organizacion_id integer NOT NULL,
isactive character(1) NOT NULL DEFAULT 'Y'::bpchar,
created timestamp without time zone NOT NULL DEFAULT now(),
createdby numeric(10,0) NOT NULL,
updated timestamp without time zone NOT NULL DEFAULT now(),
updatedby numeric(10,0) NOT NULL,
tipo_ganado character varying(80) NOT NULL,
ganado_id integer NOT NULL,
CONSTRAINT ganado_tipo_ganado_pk PRIMARY KEY (ganado_tipo_ganado_id),
CONSTRAINT ganado_fk FOREIGN KEY (ganado_id)
REFERENCES agroapp.ganado (ganado_id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION
)
CREATE TABLE agroapp.ganado
(
ganado_id serial NOT NULL,
organizacion_id integer NOT NULL,
isactive character(1) NOT NULL DEFAULT 'Y'::bpchar,
created timestamp without time zone NOT NULL DEFAULT now(),
createdby numeric(10,0) NOT NULL,
updated timestamp without time zone NOT NULL DEFAULT now(),
updatedby numeric(10,0) NOT NULL,
fecha_nacimiento timestamp without time zone NOT NULL,
tipo_ganado character varying(80) NOT NULL,
diio_id integer NOT NULL,
fundo_id integer NOT NULL,
raza_id integer NOT NULL,
estado_reproductivo character varying(80) NOT NULL,
estado_leche character varying(80),
CONSTRAINT ganado_pk PRIMARY KEY (ganado_id),
CONSTRAINT diio_fk FOREIGN KEY (diio_id)
REFERENCES agroapp.diio (diio_id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION,
CONSTRAINT fundo_fk FOREIGN KEY (fundo_id)
REFERENCES agroapp.fundo (fundo_id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION,
CONSTRAINT raza_fk FOREIGN KEY (raza_id)
REFERENCES agroapp.raza (raza_id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION
)

Answer 1

Most probably because the forced cast voids the option to use an index on the column agroapp.ganado_fundo.created
Guessing (for lack of information) that gf.created is of type timestamp with time zone (or timestamp), replace
AND gf.created::DATE <= '20181030'::DATE
with:
AND gf.created < '2018-10-31'::timestamp -- match the data type of the column!
to achieve the same result, but with index support.
If you operate with timestamtptz, be aware of implications on the date: it depends on the current time zone. Details:
Ignoring time zones altogether in Rails and PostgreSQL