From ca871e71e6f082f20bdafba2450030f12f9d144c Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Tue, 2 Jul 2013 12:21:16 -0400
Subject: [PATCH] Mention extra_float_digits in floating point docs
Make it easier for readers of the FP docs to find out about possibly
truncated values.
Per complaint from Tom Duffey in message
F0E0F874-C86F-48D1-AA2A-0C5365BF5118@trillitech.com
Author: Albe Laurenz
Reviewed by: Abhijit Menon-Sen
---
doc/src/sgml/config.sgml | 1 +
doc/src/sgml/datatype.sgml | 11 +++++++++++
2 files changed, 12 insertions(+)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3d0d55b47d6..f5b6868569e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -5244,6 +5244,7 @@ SET XML OPTION { DOCUMENT | CONTENT };
partially-significant digits; this is especially useful for dumping
float data that needs to be restored exactly. Or it can be set
negative to suppress unwanted digits.
+ See also <xref linkend="datatype-float">.
</para>
</listitem>
</varlistentry>
diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
index 7f6e661adb3..91d008c2975 100644
--- a/doc/src/sgml/datatype.sgml
+++ b/doc/src/sgml/datatype.sgml
@@ -691,6 +691,17 @@ NUMERIC
from zero will cause an underflow error.
</para>
+ <note>
+ <para>
+ The <xref linkend="guc-extra-float-digits"> setting controls the
+ number of extra significant digits included when a floating point
+ value is converted to text for output. With the default value of
+ <literal>0</literal>, the output is the same on every platform
+ supported by PostgreSQL. Increasing it will produce output that
+ more accurately represents the stored value, but may be unportable.
+ </para>
+ </note>
+
<indexterm>
<primary>not a number</primary>
<secondary>double precision</secondary>
--
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