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BUG #6420: Incorrect description of Postgres time system

From: tom(dot)mcglynn(at)nasa(dot)gov
To: pgsql-bugs(at)postgresql(dot)org
Subject: BUG #6420: Incorrect description of Postgres time system
Date: 2012-01-30 22:30:00
Message-ID: E1Rrzjc-00058m-Ph@wrigleys.postgresql.org (view raw or flat)
Thread:
Lists: pgsql-bugs
The following bug has been logged on the website:

Bug reference:      6420
Logged by:          Thomas McGlynn
Email address:      tom(dot)mcglynn(at)nasa(dot)gov
PostgreSQL version: 9.1.2
Operating system:   Any
Description:        

As part of our preparations for the leap second this year I wanted to see
how Postgres handles this.  The only information I could see was

(Technically, PostgreSQL uses UT1 because 
leap seconds are not handled.)

in section 9.9 of the manual.  This seems to be a misapprehension of what
the UT1 time system is.  UT1 measures mean solar time -- days are not
exactly 86400 seconds long.  Currently UT1 and UTC never differ by more than
one second.  Leap seconds are the way this correspondence is kept. What I
believe you should be saying is that you use TAI -- atomic time -- with some
offset.

If my inferences from the documentation is correct and Postgres measures the
number of seconds from UTC 2000-01-01, then the time system used is TAI-32
seconds.   See http://stjarnhimlen.se/comp/time.html for details (and to
check whether I got the sign right!).

I think this should be clearly stated in the documentation when discussing
the time types but I did not see it.

Regards...


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Subject: BUG #6421: Revoke column level privilage
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