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PL/Python array support

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Support arrays as parameters and return values of PL/Python functions.
This commit is contained in:
Peter Eisentraut
2009-12-10 20:43:40 +00:00
parent a37b001b80
commit db7386187f
4 changed files with 343 additions and 4 deletions
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39
doc/src/sgml/plpython.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/plpython.sgml,v 1.40 2009/03/30 16:15:43 alvherre Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/plpython.sgml,v 1.41 2009/12/10 20:43:40 petere Exp $ -->
<chapter id="plpython">
<title>PL/Python - Python Procedural Language</title>
@ -134,6 +134,43 @@ $$ LANGUAGE plpythonu;
function is strict or not.
</para>
<para>
SQL array values are passed into PL/Python as a Python list. To
return an SQL array value out of a PL/Python function, return a
Python sequence, for example a list or tuple:
<programlisting>
CREATE FUNCTION return_arr()
RETURNS int[]
AS $$
return (1, 2, 3, 4, 5)
$$ LANGUAGE plpythonu;
SELECT return_arr();
return_arr
-------------
{1,2,3,4,5}
(1 row)
</programlisting>
Note that in Python, strings are sequences, which can have
undesirable effects that might be familiar to Python programmers:
<programlisting>
CREATE FUNCTION return_str_arr()
RETURNS varchar[]
AS $$
return "hello"
$$ LANGUAGE plpythonu;
SELECT return_str_arr();
return_str_arr
----------------
{h,e,l,l,o}
(1 row)
</programlisting>
</para>
<para>
Composite-type arguments are passed to the function as Python mappings. The
element names of the mapping are the attribute names of the composite type.