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
---
Kevin Pollard | PODBA (Pretend Oracle DBA)
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
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| Brian McGraw -- Oracle
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Received on Wed Dec 19 2001 - 10:53:04 CST
