<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>

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.

</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>

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 convertedto<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>