Request for improvement: Allow to push (t.o).id via GROUP BY ocd.o

Hello PostgreSQL-development,

something's stopping the planner from being able to deduce that (t.o).id is safe to push through a GROUP BY ocd.o

        SELECT * FROM (
                        SELECT
                                sum( t.group_suma ) OVER( PARTITION BY t.id ) AS total_suma,
--                              sum( t.group_suma ) OVER( PARTITION BY (t.o).id ) AS total_suma,  -- For any WHERE this
takes2700ms
 
                                *
                        FROM (
                                SELECT
                                 sum( ocd.item_cost     ) AS group_cost,
                                 sum( ocd.item_suma     ) AS group_suma,
                                 max( (ocd.ic).consumed ) AS consumed,
                                 (ocd.ic).consumed_period,
                                 ocd.o,
                                 (ocd.o).id
                                FROM order_cost_details( tstzrange( '2019-04-01', '2019-05-01' ) ) ocd
                                GROUP BY ocd.o, (ocd.o).id, (ocd.ic).consumed_period
                        ) t
        ) t
        WHERE t.id = 6154 AND t.consumed_period @> '2019-04-01'::timestamptz       -- This takes 2ms
--      WHERE (t.o).id = 6154 AND t.consumed_period @> '2019-04-01'::timestamptz   -- This takes 2700ms


More info is here: https://stackoverflow.com/q/57003113/4632019

-- 
Best regards,
Eugen Konkov