From 44f7afba79348883da110642d230a13003b75f62 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 4 Jan 2017 16:30:16 -0500
Subject: [PATCH] Improve documentation of timestamp internal representation.
Be more clear that we represent timestamps in microseconds when
integer timestamps are used, and in fractional seconds when
floating-point timestamps are used.
Discussion: http://postgr.es/m/20161212135045.GB15488@e733.localdomain
Report by Alexander Alekseev. Wording by me with a suggestion
from Tom Lane.
---
doc/src/sgml/datatype.sgml | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
index 464ce83d30e..3bc6854be65 100644
--- a/doc/src/sgml/datatype.sgml
+++ b/doc/src/sgml/datatype.sgml
@@ -1651,13 +1651,14 @@ SELECT E'\\xDEADBEEF';
<para>
When <type>timestamp</> values are stored as eight-byte integers
(currently the default), microsecond precision is available over
- the full range of values. When <type>timestamp</> values are
- stored as double precision floating-point numbers instead (a
- deprecated compile-time option), the effective limit of precision
- might be less than 6. <type>timestamp</type> values are stored as
- seconds before or after midnight 2000-01-01. When
- <type>timestamp</type> values are implemented using floating-point
- numbers, microsecond precision is achieved for dates within a few
+ the full range of values. In this case, the internal representation
+ is the number of microseconds before or after midnight 2000-01-01.
+ When <type>timestamp</> values are stored as double precision
+ floating-point numbers (a deprecated compile-time option), the
+ internal representation is the number of seconds before or after
+ midnight 2000-01-01. With this representation, the effective limit
+ of precision might be less than 6; in practice,
+ microsecond precision is achieved for dates within a few
years of 2000-01-01, but the precision degrades for dates further
away. Note that using floating-point datetimes allows a larger
range of <type>timestamp</type> values to be represented than
--
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