Reducing loading times by a tenfold with Postgres aggregations

seed.sql

-- Start an instance of postgres
-- docker run --name db -p 5432:5432 -e POSTGRES_HOST_AUTH_METHOD=trust postgres:latest

CREATE DATABASE veterinary;

CREATE TABLE person (
	id UUID PRIMARY KEY,
	name TEXT
);

CREATE TABLE animal (
	id UUID PRIMARY KEY,
	owner_id UUID NOT NULL,
	type TEXT NOT NULL,
	name TEXT NOT NULL,
	FOREIGN KEY(owner_id) REFERENCES person(id)
);

CREATE INDEX animal_owner_id ON animal(owner_id uuid_ops);

CREATE TABLE vaccine(
	id UUID PRIMARY KEY,
	name TEXT
);

CREATE TABLE animal_vaccine(
	vaccine_id UUID,
	animal_id UUID,
	applied_on TIMESTAMP,
	PRIMARY KEY(vaccine_id, animal_id),
	FOREIGN KEY(vaccine_id) REFERENCES vaccine(id),
	FOREIGN KEY(animal_id) REFERENCES animal(id)
);

CREATE INDEX animal_vaccine_animal_id ON animal_vaccine(animal_id uuid_ops);
CREATE INDEX animal_vaccine_vaccine_id ON animal_vaccine(vaccine_id uuid_ops);

INSERT INTO person(id, name)
VALUES ('fbab22a3-f7bc-422c-942f-d184ad189e29', 'Pablo');

INSERT INTO animal(id, owner_id, type, name) VALUES
('5f2461a9-6c62-453e-9182-38cd0fa76e01', 'fbab22a3-f7bc-422c-942f-d184ad189e29', 'cat', 'Bills');

INSERT INTO vaccine(id, name) VALUES 
('0ee28253-5b94-4096-926c-d33ceb22d24d', 'Feline herpesvirus'),
('6cf5487a-ba06-42e7-9e80-226590752a77', 'Rabies');

INSERT INTO animal_vaccine(vaccine_id, animal_id, applied_on) VALUES
('0ee28253-5b94-4096-926c-d33ceb22d24d', '5f2461a9-6c62-453e-9182-38cd0fa76e01', '2021-02-10'),
('6cf5487a-ba06-42e7-9e80-226590752a77', '5f2461a9-6c62-453e-9182-38cd0fa76e01', '2022-02-10');