CREATE TABLE mytable (id serial PRIMARY KEY);
CREATE OR REPLACE FUNCTION get_random_value_with_seed(int, int)
RETURNS double precision AS $$
    DECLARE result double precision;
    BEGIN
        PERFORM setseed(($2/200.0) + ($1 / 429490.0));
        SELECT RANDOM() INTO result;
        RAISE NOTICE 'seeded random value: %', result;
        RETURN result;
    END $$
LANGUAGE plpgsql IMMUTABLE;
\copy mytable FROM 'file_containing_ints';
CREATE INDEX seeded_random_1 ON mytable (get_random_value_with_seed(id, 1));
SELECT id FROM mytable ORDER BY get_random_value_with_seed(id, 1) LIMIT 5;
EXPLAIN ANALYZE VERBOSE SELECT id FROM mytable ORDER BY get_random_value_with_seed(id, 1) LIMIT 5;