Re: Re: Timestamp with vs without time zone. - Mailing list pgsql-general

From Peter J. Holzer
Subject Re: Re: Timestamp with vs without time zone.
Date
Msg-id YUooOlUZrmcJKHAg@hjp.at
Whole thread Raw
In response to Re: Re: Timestamp with vs without time zone.  (Dave Cramer <davecramer@postgres.rocks>)
Responses Re: Timestamp with vs without time zone.  (Adrian Klaver <adrian.klaver@aklaver.com>)
List pgsql-general
On 2021-09-21 13:43:46 -0400, Dave Cramer wrote:
>
>
> On Tue, 21 Sept 2021 at 13:40, Peter J. Holzer <hjp-pgsql@hjp.at> wrote:
>
>     On 2021-09-21 13:34:21 -0400, Dave Cramer wrote:
>     > On Tue, 21 Sept 2021 at 13:20, Peter J. Holzer <hjp-pgsql@hjp.at> wrote:
>     >     On 2021-09-21 20:50:44 +1200, Tim Uckun wrote:
>     >     Calling a type which doesn't include a timezone
>     >     "timestamp with timezone" is - how do I put this? - more than just
>     >     weird.
>     >
>     > I would say this is a perspective thing. It's a timestamp with a time
>     > zone from the client's perspective.
>
>     I disagree. When I read back the value the original timezone is lost. So
>     it clearly DOESN'T store the timestamp WITH the timezone.
>
>
> I never said it stored the timezone.  I said that it has a timezone. 

The raison d’être of a database is to store data. If some data isn't
stored, the database doesn't have it, in my opinion.

As a different example, I can store a number with 15 decimal digits in a float4
and I can get 15 decimal digits out again:

hjp=> create table t (f float4);
CREATE TABLE
hjp=> insert into t(f) values(1.23456789012345);
INSERT 0 1
hjp=> select f::float8::numeric from t;
╔══════════════════╗
║        f         ║
╟──────────────────╢
║ 1.23456788063049 ║
╚══════════════════╝
(1 row)

But those digits aren't the same I stored. So a float4 doesn't "have" 15
decimal digits of accuracy. Not even 8, although in this specific case
the first 8 digits happen to be correct.

        hp

--
   _  | Peter J. Holzer    | Story must make more sense than reality.
|_|_) |                    |
| |   | hjp@hjp.at         |    -- Charles Stross, "Creative writing
__/   | http://www.hjp.at/ |       challenge!"

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