pgsql: Document that age() adds days, then full months.
Log Message:
-----------
Document that age() adds days, then full months.
Modified Files:
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pgsql/doc/src/sgml:
func.sgml (r1.382 -> r1.383)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml.diff?r1=1.382&r2=1.383)
momjian@postgresql.org (Bruce Momjian) writes:
Document that age() adds days, then full months.
AFAICT, this documentation "improvement" is outright wrong.
regards, tom lane
Tom Lane wrote:
momjian@postgresql.org (Bruce Momjian) writes:
Document that age() adds days, then full months.
AFAICT, this documentation "improvement" is outright wrong.
I am now thinking no documentation paragraph is even needed. We have to
use the number of months in the earlier date or simple computations
would not work like:
test=> select age('2004-05-29', '2004-06-28');
age
----------
-30 days
(1 row)
The end of the earlier month is part of the interval between the two
timestamps, while the end of the later month is not. Of course with a
multi-months span there are more chances for variance, but we certainly
should give the right answer for an interval < 1 month. I can just add
a C comment.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
Bruce Momjian wrote:
Tom Lane wrote:
momjian@postgresql.org (Bruce Momjian) writes:
Document that age() adds days, then full months.
AFAICT, this documentation "improvement" is outright wrong.
I am now thinking no documentation paragraph is even needed. We have to
use the number of months in the earlier date or simple computations
would not work like:test=> select age('2004-05-29', '2004-06-28');
age
----------
-30 days
(1 row)The end of the earlier month is part of the interval between the two
timestamps, while the end of the later month is not. Of course with a
multi-months span there are more chances for variance, but we certainly
should give the right answer for an interval < 1 month. I can just add
a C comment.
I have updated the documentation to read:
Note there can be ambiguity in the <literal>months</> returned by
<function>age</> because different months have a different number of
days. <productname>PostgreSQL</>'s approach uses the month from the
earlier of the two dates when calculating partial months. For example,
<literal>age('2004-06-01', '2004-04-30')</> uses April to yield
<literal>1 mon 1 day</>, while using May would yield <literal>1 mon 2
days</> because May has 31 days, while April has only 30.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +