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
This commit is contained in:
Alvaro Herrera 2013-07-02 12:21:16 -04:00
parent ae8fc62406
commit 061c7a3c7a
2 changed files with 12 additions and 0 deletions

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@ -5366,6 +5366,7 @@ SET XML OPTION { DOCUMENT | CONTENT };
partially-significant digits; this is especially useful for dumping partially-significant digits; this is especially useful for dumping
float data that needs to be restored exactly. Or it can be set float data that needs to be restored exactly. Or it can be set
negative to suppress unwanted digits. negative to suppress unwanted digits.
See also <xref linkend="datatype-float">.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>

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@ -681,6 +681,17 @@ NUMERIC
from zero will cause an underflow error. from zero will cause an underflow error.
</para> </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> <indexterm>
<primary>not a number</primary> <primary>not a number</primary>
<secondary>double precision</secondary> <secondary>double precision</secondary>