Timestamp (0/2/4/8)

'Przedruk' z http://www.postgres.cz/index.php/PostgreSQL_SQL_Tricks

Dropping milliseconds from timestamp

Usually we don't need timestamp value in maximum precision. For mostly people only seconds are significant. Timestamp type allows to define precision - and we could to use this feature:

postgres=# select current_timestamp;
             now              
------------------------------
 2009-05-23 20:42:21.57899+02
(1 row)

Time: 196,784 ms
postgres=# select current_timestamp::timestamp(2);
          now           
------------------------
 2009-05-23 20:42:27.74
(1 row)

Time: 51,861 ms
postgres=# select current_timestamp::timestamp(0);
         now         
---------------------
 2009-05-23 20:42:31
(1 row)

Time: 0,729 ms