Re: Why is time with timezone 12 bytes? - Mailing list pgsql-hackers

From Thom Brown
Subject Re: Why is time with timezone 12 bytes?
Date
Msg-id AANLkTimwGa6H80kvKOW17bcG8tswjXExn+vEn0cTq0Um@mail.gmail.com
Whole thread Raw
In response to Why is time with timezone 12 bytes?  (Josh Berkus <josh@agliodbs.com>)
Responses Re: Why is time with timezone 12 bytes?  (Kenneth Marshall <ktm@rice.edu>)
List pgsql-hackers
On 22 September 2010 22:01, Josh Berkus <josh@agliodbs.com> wrote:
> All,
>
> I was just checking on our year-2027 compliance, and happened to notice
> that time with time zone takes up 12 bytes.  This seems peculiar, given
> that timestamp with time zone is only 8 bytes, and at my count we only
> need 5 for the time with microsecond precision.  What's up with that?
>
> Also, what is the real range of our 8-byte *integer* timestamp?

The time is 8 bytes, (1,000,000 microseconds * 60 minutes, * 24 hours
= 1,440,000,000 microseconds = 31 bits = 8 bytes).

The timezone displacement takes up to 12 bits, meaning 3 bytes.
(1460+1459 = 2919 = 12 bits = 3 bytes).  So that's 11 bytes.  Not sure
where the extra 1 byte comes from.

--
Thom Brown
Twitter: @darkixion
IRC (freenode): dark_ixion
Registered Linux user: #516935


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