NTP again

[Nobody's Hero]

OK riddle me this....

If setting the time backwards in a unix/oracle environment is bad. Than how does the system set the clock backwards (fall) during daylight savings time with no recourse to the Oracle DB's.......

[Rita C Workman · Accepted solution]

Robert,

Note what was said in the earlier thread...it "drifts it back" or really what it does is run time slower till everything is as it should be.

This is a once a year occurence...when time springs forward, it is not as difficult a scenario. It is far easier to handle moving time forward, than handle slowing things down to set time backwards.

/rcw

[Steven E. Protter]

Oracle keeps time in an internal format. It adjusts for daylight savings time and stores time in its internal format.

I think thats the number of clock ticks since 1970. Thats how Unix keeps time if I recall.

SEP

[Pete Randall]

Robert,

Here's another "theory" for you:

As Steven say, the time internally stays the same. It's the number of ticks since some specific date. That doesn't change. When the time changes for DST, all you're seeing is the way it's displayed changing. The database continues merrily along using the internal "number of ticks" time.


Pete

[John Poff]

Hi Robert,

Your Unix box keeps track of time in GMT. The time zone machinery massages that date and time to display an offset for your local timezone. When you have a DST change, the internal time stays on GMT and doesn't change. Unix just changes how it displays it by adding or subtracting an hour as needed.

JP

[Robert-Jan Goossens]

Hi Robert,

Here is a good doc about the diff between TZ environment variable and the kernel timezone.

Matching TZ variable (set_parms timezone) and kernel parameter ?
DocId: KBRC00007429

http://www2.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000066944960

Hope this helps,
Robert-Jan

[Jeff Schussele]

And I believe when the Oracle DB displays time for the period covering the "fall back" you'll see the shift from ?DT to ?ST.
So you go from 01:59:59 CDT to 01:00:00 CST & that will not blow up a DB.
And as noted the UNIX clock is just counting seconds from 00:00:00 (midnight) 1/1/70.

Rgds,
Jeff