ALTER TABLE roads ADD COLUMN length integer;
UPDATE roads SET length = st_length(st_transform(geom,2100));
ALTER TABLE roads ADD COLUMN reverse_cost double precision;
UPDATE roads SET reverse_cost = length;
ALTER TABLE roads ADD COLUMN "source" integer;
ALTER TABLE roads ADD COLUMN "target" integer;
SELECT pgr_createTopology('roads', 0.0005, 'geom', 'id');
SELECT seq, id1 AS node, id2 AS edge, cost FROM pgr_dijkstra('
            SELECT id AS id,
                     source::integer,
                     target::integer,
                     length::double precision AS cost
                    FROM roads',
            number1, number2, false, false);