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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Mabye OT: Was Re: Different clocks for different instances.
Oracle uses the original start date of the Gregorian calendar in October 1582:
1* select to_date('04-OCT-1582'), to_date('04-OCT-1582')+1 from dual devp> /
TO_DATE('04-OCT-1582 TO_DATE('04-OCT-1582
-------------------- --------------------04-OCT-1582 00:00:00 15-OCT-1582 00:00:00 Ben Schilling
-----Original Message-----
Sent: Wednesday, December 19, 2001 11:09 AM
To: Multiple recipients of list ORACLE-L
Well I say,
that is also the case on Tru64 as well.
How pedantic is UNIX ??
-----Original Message-----
Sent: 19 December 2001 16:16
To: Multiple recipients of list ORACLE-L
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 <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
---
Kevin Pollard | PODBA (Pretend Oracle DBA) mailto:kpollard_at_scu.edu.au <mailto:kpollard_at_scu.edu.au> | Administrative Systems Unit
Phone:+61 (02) 6620 3969 | Southern Cross University
FAX:+61 (02) 6626 9122 | P.O. Box 157
Room: R1-40a | Lismore NSW 2480, Australia
http://staff.scu.edu.au/asu/index.html
<http://staff.scu.edu.au/asu/index.html>
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Author: Kevin Pollard
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Author: Schilling, Ben
INET: Ben.Schilling_at_oci.state.wi.us
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