RE: Mabye OT: Was Re: Different clocks for different instances.

Wed, 19 Dec 2001 12:18:33 -0800

Ah, but check 10/5-16/1582 for Oracle. That is when the Gregorian calandar was adopted. 1752 is just for England (I believe).
 
Henry
-----Original Message-----
From: Robertson Lee - lerobe [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, December 19, 2001 12:09 PM
To: Multiple recipients of list ORACLE-L
Subject: RE: Mabye OT: Was Re: Different clocks for different instances.

Well I say,
 
that is also the case on Tru64 as well.
 
How pedantic is UNIX ??
 

-----Original Message-----
From: Brian McGraw [mailto:[EMAIL PROTECTED]]
Sent: 19 December 2001 16:16
To: Multiple recipients of list ORACLE-L
Subject: Mabye OT: Was Re: Different clocks for different instances.

Speaking of the system clock, here's something interesting that I stumbled across a few years back...

Background:  For those of you who may not know, the Julian calendar was abandoned by England, in favor of the Gregorian calendar, in 1752 because of date discrepancies.  To facilitate this, September 3 - 13 were eliminated.  This is actually reflected in UNIX (well, Solaris anyway) by issuing the 'cal 1752' command and looking at the month of September:

        Jul                    Aug                    Sep
 S  M Tu  W Th  F  S    S  M Tu  W Th  F  S    S  M Tu  W Th  F  S
          1  2  3  4                      1          1  2 14 15 16
 5  6  7  8  9 10 11    2  3  4  5  6  7  8   17 18 19 20 21 22 23
12 13 14 15 16 17 18    9 10 11 12 13 14 15   24 25 26 27 28 29 30
19 20 21 22 23 24 25   16 17 18 19 20 21 22
26 27 28 29 30 31      23 24 25 26 27 28 29

More info. on why the switch over occurred is available at http://www.bicknell.net/books/pc1981/p_calender.htm, for those of you with morbid curiosity.

Anyway - I was doing some Y2K testing a few years back, and playing with NLS_DATE_FORMAT queries when I learned this little tidbit.  I decided to test the Oracle date formats because - hey - they'll be okay because they're based on Unix, right?

Wrong:  Issue the following query:

select     sysdate
            ,add_months(sysdate,-2988)
            ,add_months(sysdate,-2988) - 10
from dual;

And see the following results:

SYSDATE              ADD_MONTHS(SYSDATE,- ADD_MONTHS(SYSDATE,-
-------------------- -------------------- --------------------
19-DEC-2001 10:07:02 19-DEC-1752 10:07:02 09-DEC-1752 10:07:02

The third column represents a date which, technically, does not exist.  : )

Brian

Kimberly Smith wrote:

Oracle uses the system clock.  So I would have to say no.

-----Original Message-----
Pollard
Sent: Tuesday, December 18, 2001 6:50 PM
To: Multiple recipients of list ORACLE-L

Gooday Oraclers,
is it possible to have different instances, on the same dB server,
operating with different clocks - ie different date/times?

Environment: Compaq-Digital Tru64 Unix, Oracle 8.0.6, DS20

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