DROP FUNCTION IF EXISTS insert_node(CHARACTER VARYING,INTEGER,INTEGER);
CREATE OR REPLACE FUNCTION insert_node(TABLE_NAME VARCHAR, id INT, pid INT) RETURNS void LANGUAGE PLPGSQL AS $$
BEGIN
    EXECUTE format(
        'INSERT INTO %I_relation(ancestor, descendant, distance)
        SELECT ancestor, $1 as descendant, distance + 1
        FROM %I_relation WHERE descendant = $2
        UNION ALL SELECT $3, $4, 0',
        TABLE_NAME, TABLE_NAME
    ) USING id, pid, id, id;
END;
$$;