RE: ** impact of time clock changes on Running Oracle DB

  • From: "Hostetter, Jay M" <JHostetter@xxxxxxxxxxxxxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 25 Feb 2005 07:40:02 -0500

There are no ill effects, except as mentioned for possible recovery
scenarios to a particular point in time.
If you are using DATE datatypes in your tables, you're OK.  Just be
aware that when you update these DATE datatypes from SYSDATE, you will
be using the value of the system clock (which you have adjusted -
whether it be a correct or incorrect time).  I think Dick is saying that
"tiemstamp with local timezone" is always converted to GMT.

One other thing to remember when you are fooling with the system clock -
cron jobs and database jobs may suddenly think they need to run.  In
1999 I had the brilliant idea of setting my PC clock to some date in
2000 to test a potential Y2K problem that I read about.  I was using
Groupwise at the time for email and appointments.  Suddenly I got
hundreds of alerts/alarms for all the meetings that I had scheduled
between the actual date and the new date I had just set on my PC!


-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Ramesh FL
Sent: Thursday, February 24, 2005 8:54 PM
To: DGoulet@xxxxxxxx
Cc: ajoshi977@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: Re: ** impact of time clock changes on Running Oracle DB


Will I be right in assuming that while table with columns of type
"timestamp with local Timezone"  will not be affected but tables with
"date" columns and hence the application be affected? Even in 10g there
must be some tables with column type "date" and so it may have some
impact (like Mladen implies).


On Thu, 24 Feb 2005 17:07:53 -0500, Goulet, Dick <DGoulet@xxxxxxxx>
> Joshi,
>        I'm going to make the assumption that your running Oracle 9i or

> 10g.  Maybe that's a bad assumption, but you can correct me if I'm=20
> wrong.  Reason that I mention this is that if your using "timestamp=20
> with local timezone"  as your date data type then there is no time=20
> change as far as the database is concerned.  This is because Oracle=20
> converts the local date/time to GMT, or Greenwich Mean Time or ZULU,=20
> before storing it and GMT does not change at all.  Otherwise you=20
> should see absolutely no problems.  Been happening to my servers twice

> a year for 13 years now.
> -----Original Message-----
> From: A Joshi [mailto:ajoshi977@xxxxxxxxx]=3D20
> Sent: Thursday, February 24, 2005 3:38 PM
> To: oracle-l@xxxxxxxxxxxxx
> Subject: ** impact of time clock changes on Running Oracle DB
> Hi,
>  I would like to know the impact of changing the time on my UNIX=20
> machine. how would it impact a ORACLE database running on the server.=20
> I think Oracle takes its sysdate from the UNIX. Thanks for your=20
> help.=3D20

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