diff options
| -rw-r--r-- | doc/src/sgml/plpython.sgml | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/doc/src/sgml/plpython.sgml b/doc/src/sgml/plpython.sgml index c838c7b79a5..015bbad8dda 100644 --- a/doc/src/sgml/plpython.sgml +++ b/doc/src/sgml/plpython.sgml @@ -288,8 +288,9 @@ $$ LANGUAGE plpythonu; <sect2> <title>Data Type Mapping</title> <para> - Function arguments are converted from their PostgreSQL type to a - corresponding Python type: + When a PL/Python function is called, its arguments are converted from + their PostgreSQL data type to a corresponding Python type: + <itemizedlist> <listitem> <para> @@ -322,7 +323,7 @@ $$ LANGUAGE plpythonu; 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, + than <literal>decimal</literal>. In Python 3.3 and up, however, <literal>cdecimal</literal> has been integrated into the standard library under the name <literal>decimal</literal>, so there is no longer any difference. @@ -356,8 +357,9 @@ $$ LANGUAGE plpythonu; </para> <para> - Function return values are converted to the declared PostgreSQL - return data type as follows: + When a PL/Python function returns, its return value is converted to the + function's declared PostgreSQL return data type as follows: + <itemizedlist> <listitem> <para> @@ -373,16 +375,18 @@ $$ LANGUAGE plpythonu; When the PostgreSQL return type is <type>bytea</type>, the return value will be converted to a string (Python 2) or bytes (Python 3) using the respective Python built-ins, with the - result being converted <type>bytea</type>. + result being converted to <type>bytea</type>. </para> </listitem> <listitem> <para> - For all other PostgreSQL return types, the returned Python - value is converted to a string using the Python - built-in <literal>str</literal>, and the result is passed to the - input function of the PostgreSQL data type. + For all other PostgreSQL return types, the return value is converted + to a string using the Python built-in <literal>str</literal>, and the + result is passed to the input function of the PostgreSQL data type. + (If the Python value is a <type>float</>, it is converted using + the <literal>repr</> built-in instead of <literal>str</literal>, to + avoid loss of precision.) </para> <para> |