DO
$$
    DECLARE
        previous_version CONSTANT text := 'v1.5.1';
        next_version     CONSTANT text := 'v1.5.2';
    BEGIN
        IF (SELECT openreplay_version()) = previous_version THEN
            raise notice 'valid previous DB version';
        ELSEIF (SELECT openreplay_version()) = next_version THEN
            raise notice 'new version detected, nothing to do';
        ELSE
            RAISE EXCEPTION 'upgrade to % failed, invalid previous version, expected %, got %', next_version,previous_version,(SELECT openreplay_version());
        END IF;
    END ;
$$
LANGUAGE plpgsql;

BEGIN;
CREATE OR REPLACE FUNCTION openreplay_version()
    RETURNS text AS
$$
SELECT 'v1.5.2'
$$ LANGUAGE sql IMMUTABLE;

COMMIT;