Postgresql query test

query_test.sql

CREATE SCHEMA IF NOT EXISTS my_test;

DROP TABLE IF EXISTS my_test.my_table;
DROP TABLE IF EXISTS my_test.a_table CASCADE;
DROP TABLE IF EXISTS my_test.a_b_relation;

CREATE TABLE my_test.my_table (
        a                               integer,
        b                               integer
);

CREATE TABLE my_test.a_table (
        a                               integer PRIMARY KEY
);

CREATE TABLE my_test.a_b_relation (
        a                               integer REFERENCES my_test.a_table (a),
        b                               integer
);

CREATE OR REPLACE FUNCTION row_generator() RETURNS integer AS $$
        BEGIN
                FOR i in 1..1000000 LOOP
                        INSERT INTO my_test.my_table (SELECT CAST (RANDOM() * 1000 AS INT), CAST (RANDOM() * 1000 AS INT));
                END LOOP;

                RETURN (SELECT COUNT(*) FROM my_test.my_table);
        END;
$$ language plpgsql;

SELECT * FROM row_generator();

INSERT INTO my_test.a_table (SELECT DISTINCT a FROM my_test.my_table);

SELECT COUNT(*) AS "unique a in a_table" FROM my_test.a_table;

INSERT INTO my_test.a_b_relation (SELECT * FROM my_test.my_table);

SELECT COUNT(*) AS "a-b relations" FROM my_test.a_b_relation;

EXPLAIN ANALYZE VERBOSE SELECT b FROM my_test.my_table WHERE a = 10;

EXPLAIN ANALYZE VERBOSE SELECT b FROM my_test.a_b_relation, my_test.a_table
	                WHERE my_test.a_table.a = my_test.a_b_relation.a AND my_test.a_table.a = 10;