(Shoot! My previous email was another sent before it was quite ready. My
apologies to all.)
-regarding specialized needs for date/time calculations:
An alternative (but way overkill for sqlite, right?) is to use specialized
software to keep atomic time (TAI), or it's cousin, the GPS epoch time,
neither of which take heed of leap seconds. To calculate very precise
times in the past, then convert to ordinary time, the software needs to
contain
a list of past leap seconds, and of course to have that list updated as
future leap seconds are announced.
I would think a general database program would do as sqlite does -- call the
carefully written, standard posix routines (or their PC or MAC analogues),
and massage the data with some "generally recognized as safe" algorithms.
If you're doing something really unusual, you can incorporate more
sophisticated time schemes in the application or incorporate into a
specialized sqlite source.
D. J. Bernstein disliked the unix conventions, and wrote some free software
to keep TAI time:
http://cr.yp.to/proto/utctai.html
http://cr.yp.to/libtai.html
And here's a tcl script for dealing in GPS time:
http://ldas-cit.ligo.caltech.edu/doc/tcl_docs/html/gpstimetcl.html#leapSecs
Unix epoch
http://en.wikipedia.org/wiki/Unix_epoch
Yet more systems of time:
http://tycho.usno.navy.mil/systime.html
Interesting note from Naval Observatory:
http://tycho.usno.navy.mil/leapsec.html
As of 1 January 1999 [and should still be true until the next leapsecond]
TAI is ahead of UTC by 32 seconds.
TAI is ahead of GPS by 19 seconds.
GPS is ahead of UTC by 13 seconds.
--
BTW, there will definitely NOT be a leap second this June. Leap seconds
*can* be negative as well as positive, but we've never had a negative one,
and won't likely see one (as the moon keeps slowing us down with tidal
friction).
[Writing only for myself, and not on behalf of my company.]
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