From 7919398bac8bacd75ec5d763ce8b15ffaaa3e071 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Fri, 5 Jul 2013 22:41:25 -0400
Subject: PL/Python: Convert numeric to Decimal

The old implementation converted PostgreSQL numeric to Python float,
which was always considered a shortcoming.  Now numeric is converted to
the Python Decimal object.  Either the external cdecimal module or the
standard library decimal module are supported.

From: Szymon Guz <mabewlun@gmail.com>
From: Ronan Dunklau <rdunklau@gmail.com>
Reviewed-by: Steve Singer <steve@ssinger.info>
---
 doc/src/sgml/plpython.sgml | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

(limited to 'doc/src')

diff --git a/doc/src/sgml/plpython.sgml b/doc/src/sgml/plpython.sgml
index aaf758d4959..ad89355d60d 100644
--- a/doc/src/sgml/plpython.sgml
+++ b/doc/src/sgml/plpython.sgml
@@ -310,12 +310,23 @@ $$ LANGUAGE plpythonu;
 
      <listitem>
       <para>
-       PostgreSQL <type>real</type>, <type>double</type>,
-       and <type>numeric</type> are converted to
-       Python <type>float</type>.  Note that for
-       the <type>numeric</type> this loses information and can lead to
-       incorrect results.  This might be fixed in a future
-       release.
+       PostgreSQL <type>real</type> and <type>double</type> are converted to
+       Python <type>float</type>.
+      </para>
+     </listitem>
+
+     <listitem>
+      <para>
+       PostgreSQL <type>numeric</type> is converted to
+       Python <type>Decimal</type>.  This type is imported from
+       the <literal>cdecimal</literal> package if that is available.
+       Otherwise,
+       <literal>decimal.Decimal</literal> from the standard library will be
+       used.  <literal>cdecimal</literal> is significantly faster
+       than <literal>decimal</literal>.  In Python 3.3,
+       however, <literal>cdecimal</literal> has been integrated into the
+       standard library under the name <literal>decimal</literal>, so there is
+       no longer any difference.
       </para>
      </listitem>
 
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