Doc: fix discussion of how to get real Julian Dates.

Somehow I'd convinced myself that rotating to UTC-12 was the way
to do this, but upon further review, it's definitely UTC+12.

Discussion: https://postgr.es/m/1197050.1619123213@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2021-04-28 10:03:28 -04:00
parent 669f736666
commit 7cd5420230
1 changed files with 7 additions and 7 deletions

View File

@ -930,22 +930,22 @@ $ <userinput>cal 9 1752</userinput>
<para>
This definition does, however, provide a way to obtain the astronomical
definition when you need it: do the arithmetic in time
zone <literal>UTC-12</literal>. For example,
zone <literal>UTC+12</literal>. For example,
<programlisting>
=&gt; SELECT extract(julian from '2021-06-23 7:00:00-04'::timestamptz at time zone 'UTC-12');
=&gt; SELECT extract(julian from '2021-06-23 7:00:00-04'::timestamptz at time zone 'UTC+12');
date_part
--------------------
2459389.9583333335
2459388.9583333335
(1 row)
=&gt; SELECT extract(julian from '2021-06-23 8:00:00-04'::timestamptz at time zone 'UTC-12');
=&gt; SELECT extract(julian from '2021-06-23 8:00:00-04'::timestamptz at time zone 'UTC+12');
date_part
-----------
2459390
2459389
(1 row)
=&gt; SELECT extract(julian from date '2021-06-24');
=&gt; SELECT extract(julian from date '2021-06-23');
date_part
-----------
2459390
2459389
(1 row)
</programlisting>
</para>