How to set PostgreSQL's internal clock?

Posted on 2004-09-02
Last Modified: 2008-02-26

I get the PostgreSQL internal time using this command: "SELECT CURRENT_TIMESTAMP". But since I installed PostgreSQL 8.0 Beta 1 on my windows I get different times between system time and PostgreSQL time.
How to set PostgreSQL's internal clock?

Question by:pepoclv
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Author Comment

ID: 11967550
Look at this example:

Windows system time displays: 09/02/2004 4:53pm

PostgreSQL command "SELECT CURRENT_TIMESTAMP" returns: 09/02/2004 2:24pm

Expert Comment

ID: 11967633

AFAIK there is no internal clock in postgreSQL., it shouldn't make any sense.
I suppose it's the reason why it is still a beta version.

On my 7.4.2 works as expected, returning the system time.

LVL 32

Accepted Solution

ldbkutty earned 63 total points
ID: 11967736
Might be because the time set to some other timezone specification.

will set the time zone to your local time zone (the one that the server's operating system defaults to) and then run

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Expert Comment

ID: 11967837

In that case I'd expect a different hour, or half hour, not a complete different time.

...I've noticed right now that between 4:53 and 2:24  there's a difference of 2h29m,
that could lead the solution to a matter of time zones...

LVL 22

Assisted Solution

by:earth man2
earth man2 earned 62 total points
ID: 11968493
You really need to define local timezone in postgresql.conf.  For me in GB I always use the following.

If you don't it returns UTC AFAIK

# - Locale and Formatting -

datestyle = 'sql, dmy'
timezone = 'Europe/London'              # actually, defaults to TZ environment setting

Author Comment

ID: 11972219
Now I know that the problem is time zone. I tryed to set local timezone doing this: SET TIME ZONE 'GMT-3'; but it did not work.
When I run SELECT CURRENT_TIMESTAMP; it returns "2004-09-03 12:47:28.093-00".
LVL 22

Expert Comment

by:earth man2
ID: 11972312
dev=# set session timezone to -3;
dev=# select current_timestamp, current_timestamp at time zone 'BST';
          timestamptz          |          timezone          
 03/09/2004 10:05:51.652133-03 | 03/09/2004 14:05:51.652133
(1 row)

LVL 22

Expert Comment

by:earth man2
ID: 12063608
I think pg_tzset  look in directory /usr/share/postgresql/timezone   GMT-3 is in the "Etc" subdirectory so this works.

dev=> set session timezone to 'Etc/GMT-3';
dev=> select current_timestamp, current_timestamp at time zone 'BST';
           timestamptz           |         timezone          
 15/09/2004 15:12:13.14708 GMT-3 | 15/09/2004 13:12:13.14708

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