How to get the timestamp column in only milliseconds from PostgreSQL? I have a column "created" with type timestamp without time zone default now() in a PostgreSQL database.

If I select colums, it has a nice and readable format per default:

SELECT created FROM mytable;

         created
---------------------------
2011-05-17 10:40:28.876944


But I would like to get the timestamp in only milliseconds (as a Long). Something like this:

SELECT myformat(created) FROM mytable;

     created
-----------------
2432432343876944


How can I get the timestamp column in only milliseconds from PostgreSQL?



Response to Jack:

I do get the same difference as you (-3600), but if I use timestamp with time zone I can see that the "error" or difference is because '1970-01-01' gets time zone +01.

create table my_table_2(created timestamp with time zone);
CREATE TABLE
insert into my_table_2 (created) values (now()), ('1970-01-01');
INSERT 0 2
select created, extract(epoch from created) from my_table_2;
            created            |    date_part
-------------------------------+------------------
 2011-05-18 11:03:16.909338+02 | 1305709396.90934
 1970-01-01 00:00:00+01        |            -3600
(2 rows)


Is the difference a bug? I may be because of "Daylight saving times" at the moment?



Also interesting while using to_timestamp() to insert timestamp 0 and 1.

insert into my_table_2 (created) values (to_timestamp(0));
INSERT 0 1

insert into my_table_2 (created) values (to_timestamp(1));
INSERT 0 1
select created, extract(epoch from created) from my_table_2;
            created            |    date_part
-------------------------------+------------------
 2011-05-18 11:03:16.909338+02 | 1305709396.90934
 1970-01-01 00:00:00+01        |            -3600
 1970-01-01 01:00:00+01        |                0
 1970-01-01 01:00:01+01        |                1
Use EXTRACT and the UNIX-Timestamp

SELECT EXTRACT(EPOCH FROM TIMESTAMP '2011-05-17 10:40:28.876944') * 1000;


would give


  1305621628876.94


Multiply it by 1000 to turn it into milliseconds. You can then convert it to whatever you want (decimal would be a good choice). Don't forget to keep the timezone in mind. JackPDouglas has such an example in his answer. Here is an excerpt from his answer (created being the column with your timetamp) that illustrates how to work with timezones:

SELECT EXTRACT(EPOCH FROM created AT TIME ZONE 'UTC') FROM my_table;