CREATE TABLE orders (id SERIAL,
                     customerID INTEGER,
                     timestamp BIGINT,
                     PRIMARY KEY(id));

CREATE VIEW lastOrders AS SELECT  id,
                                  customerID,
                                  MAX(timestamp)
                                  FROM orders
                                  GROUP BY customerID;

CREATE VIEW lastOrders AS
SELECT
DISTINCT ON (customerID)
    id,
    customerID,
    timestamp
FROM orders
ORDER BY customerID, timestamp desc;

CREATE  VIEW last_orders AS
SELECT  id, customer_id, timestamp
FROM    orders AS o
WHERE   timestamp = (
            SELECT  MAX(timestamp)
            FROM    orders AS oi
            WHERE   o.customer_id = oi.customer_id
        );

select a.*
from
    orders a,
    (select customerID, max(timestamp) timestamp
        from orders group by customerID
    ) b
where a.customer_id = b.customerID
and a.timestamp = b.timestamp