Hi, Bruce san,

From: "Bruce Momjian" <br...@momjian.us>
On Tue, Aug  6, 2013 at 12:09:53PM -0400, Tom Lane wrote:
Yes.  I don't see any reason to change it, either, as nobody has
complained that it's actually bad.  If you feel a compulsion to
change the docs, do that.

OK, seems 'Postgres' is a unique output format for 'date' too, even though
it doesn't look like the 'Postgres' timestamp output:

default
SET datestyle = 'ISO, MDY'; SELECT current_timestamp, current_date;
SET
              now              |    date
-------------------------------+------------
2013-08-06 16:18:48.218555-04 | 2013-08-06

SET datestyle = 'SQL, MDY'; SELECT current_timestamp, current_date;
SET
              now               |    date
--------------------------------+------------
08/06/2013 16:18:43.054488 EDT | 08/06/2013

SET datestyle = 'German, MDY'; SELECT current_timestamp, current_date;
SET
              now               |    date
--------------------------------+------------
06.08.2013 16:18:59.026553 EDT | 06.08.2013

MDY
SET datestyle = 'Postgres, MDY'; SELECT current_timestamp, current_date;
SET
                 now                 |    date
-------------------------------------+------------
Tue Aug 06 16:18:53.590548 2013 EDT | 08-06-2013

DMY
SET datestyle = 'Postgres, DMY'; SELECT current_timestamp, current_date;
SET
                 now                 |    date
-------------------------------------+------------
Tue 06 Aug 16:20:23.902549 2013 EDT | 06-08-2013

I don't think there is even a documentation change I can suggest.

I'm sorry I didn't respond for a long time.  I've come up with a suggestion.

The original reporter of this problem expected the output of the date type in 'Postgres,DMY' style to be "17 Dec 1997", when the output of the timestamp if "Wed 17 Dec 07:37:16 1997 PST". He thought so by reading the following sentence:

http://www.postgresql.org/docs/current/static/datatype-datetime.html
The output of the date and time types is of course only the date or time part in accordance with the given examples.

However, the actual output of the date type in Postgres style is:

* 12-17-1997 if datestyle is 'Postgres,YMD' or 'Postgres,MDY'
* 17-12-1997 if datestyle is 'Postgres,DMY'

So, my suggestion is to just add the following sentence right after the above one.

The Postgres style is an exception: the output of the date type is either MM-DD-YYYY (e.g. 12-17-1997) or DD-MM-YYYY (e.g. 17-12-1997), which is different from the date part of the output of the timestamp type.

Could you consider and add this to the manual?

Regards
MauMau





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