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Table function support for PL/Python
This allows functions with multiple OUT parameters returning both one or multiple records (RECORD or SETOF RECORD). Jan Urbański, reviewed by Hitoshi Harada
This commit is contained in:
Peter Eisentraut
361
src/pl/plpython/expected/plpython_composite.out
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361
src/pl/plpython/expected/plpython_composite.out
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CREATE FUNCTION multiout_simple(OUT i integer, OUT j integer) AS $$
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return (1, 2)
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$$ LANGUAGE plpythonu;
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SELECT multiout_simple();
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multiout_simple
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-----------------
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(1,2)
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(1 row)
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SELECT * FROM multiout_simple();
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i | j
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---+---
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1 | 2
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(1 row)
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SELECT i, j + 2 FROM multiout_simple();
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i | ?column?
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---+----------
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1 | 4
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(1 row)
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SELECT (multiout_simple()).j + 3;
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?column?
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----------
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5
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(1 row)
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CREATE FUNCTION multiout_simple_setof(n integer = 1, OUT integer, OUT integer) RETURNS SETOF record AS $$
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return [(1, 2)] * n
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$$ LANGUAGE plpythonu;
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SELECT multiout_simple_setof();
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multiout_simple_setof
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-----------------------
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(1,2)
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(1 row)
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SELECT * FROM multiout_simple_setof();
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column1 | column2
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---------+---------
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1 | 2
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(1 row)
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SELECT * FROM multiout_simple_setof(3);
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column1 | column2
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---------+---------
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1 | 2
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1 | 2
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1 | 2
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(3 rows)
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CREATE FUNCTION multiout_record_as(typ text,
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first text, OUT first text,
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second integer, OUT second integer,
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retnull boolean) RETURNS record AS $$
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if retnull:
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return None
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if typ == 'dict':
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return { 'first': first, 'second': second, 'additionalfield': 'must not cause trouble' }
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elif typ == 'tuple':
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return ( first, second )
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elif typ == 'list':
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return [ first, second ]
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elif typ == 'obj':
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class type_record: pass
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type_record.first = first
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type_record.second = second
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return type_record
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$$ LANGUAGE plpythonu;
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SELECT * FROM multiout_record_as('dict', 'foo', 1, 'f');
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first | second
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-------+--------
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foo | 1
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(1 row)
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SELECT multiout_record_as('dict', 'foo', 1, 'f');
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multiout_record_as
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--------------------
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(foo,1)
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(1 row)
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SELECT *, s IS NULL AS snull FROM multiout_record_as('tuple', 'xxx', NULL, 'f') AS f(f, s);
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f | s | snull
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-----+---+-------
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xxx | | t
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(1 row)
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SELECT *, f IS NULL AS fnull, s IS NULL AS snull FROM multiout_record_as('tuple', 'xxx', 1, 't') AS f(f, s);
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f | s | fnull | snull
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---+---+-------+-------
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| | t | t
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(1 row)
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SELECT * FROM multiout_record_as('obj', NULL, 10, 'f');
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first | second
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-------+--------
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| 10
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(1 row)
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CREATE FUNCTION multiout_setof(n integer,
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OUT power_of_2 integer,
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OUT length integer) RETURNS SETOF record AS $$
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for i in range(n):
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power = 2 ** i
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length = plpy.execute("select length('%d')" % power)[0]['length']
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yield power, length
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$$ LANGUAGE plpythonu;
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SELECT * FROM multiout_setof(3);
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power_of_2 | length
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------------+--------
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1 | 1
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2 | 1
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4 | 1
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(3 rows)
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SELECT multiout_setof(5);
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multiout_setof
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----------------
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(1,1)
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(2,1)
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(4,1)
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(8,1)
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(16,2)
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(5 rows)
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CREATE FUNCTION multiout_return_table() RETURNS TABLE (x integer, y text) AS $$
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return [{'x': 4, 'y' :'four'},
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{'x': 7, 'y' :'seven'},
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{'x': 0, 'y' :'zero'}]
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$$ LANGUAGE plpythonu;
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SELECT * FROM multiout_return_table();
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x | y
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---+-------
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4 | four
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7 | seven
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0 | zero
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(3 rows)
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CREATE FUNCTION multiout_array(OUT integer[], OUT text) RETURNS SETOF record AS $$
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yield [[1], 'a']
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yield [[1,2], 'b']
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yield [[1,2,3], None]
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$$ LANGUAGE plpythonu;
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SELECT * FROM multiout_array();
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column1 | column2
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---------+---------
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{1} | a
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{1,2} | b
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{1,2,3} |
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(3 rows)
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CREATE FUNCTION singleout_composite(OUT type_record) AS $$
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return {'first': 1, 'second': 2}
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$$ LANGUAGE plpythonu;
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CREATE FUNCTION multiout_composite(OUT type_record) RETURNS SETOF type_record AS $$
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return [{'first': 1, 'second': 2},
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{'first': 3, 'second': 4 }]
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$$ LANGUAGE plpythonu;
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SELECT * FROM singleout_composite();
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first | second
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-------+--------
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1 | 2
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(1 row)
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SELECT * FROM multiout_composite();
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first | second
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-------+--------
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1 | 2
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3 | 4
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(2 rows)
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-- composite OUT parameters in functions returning RECORD not supported yet
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CREATE FUNCTION multiout_composite(INOUT n integer, OUT type_record) AS $$
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return (n, (n * 2, n * 3))
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$$ LANGUAGE plpythonu;
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CREATE FUNCTION multiout_table_type_setof(typ text, returnnull boolean, INOUT n integer, OUT table_record) RETURNS SETOF record AS $$
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if returnnull:
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d = None
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elif typ == 'dict':
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d = {'first': n * 2, 'second': n * 3, 'extra': 'not important'}
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elif typ == 'tuple':
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d = (n * 2, n * 3)
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elif typ == 'obj':
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class d: pass
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d.first = n * 2
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d.second = n * 3
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for i in range(n):
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yield (i, d)
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$$ LANGUAGE plpythonu;
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SELECT * FROM multiout_composite(2);
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n | column2
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---+---------
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2 | (4,6)
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(1 row)
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SELECT * FROM multiout_table_type_setof('dict', 'f', 3);
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n | column2
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---+---------
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0 | (6,9)
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1 | (6,9)
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2 | (6,9)
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(3 rows)
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SELECT * FROM multiout_table_type_setof('tuple', 'f', 2);
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n | column2
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---+---------
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0 | (4,6)
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1 | (4,6)
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(2 rows)
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SELECT * FROM multiout_table_type_setof('obj', 'f', 4);
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n | column2
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---+---------
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0 | (8,12)
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1 | (8,12)
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2 | (8,12)
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3 | (8,12)
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(4 rows)
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SELECT * FROM multiout_table_type_setof('dict', 't', 3);
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n | column2
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---+---------
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0 |
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1 |
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2 |
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(3 rows)
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-- check what happens if a type changes under us
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CREATE TABLE changing (
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i integer,
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j integer
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);
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CREATE FUNCTION changing_test(OUT n integer, OUT changing) RETURNS SETOF record AS $$
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return [(1, {'i': 1, 'j': 2}),
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(1, (3, 4))]
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$$ LANGUAGE plpythonu;
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SELECT * FROM changing_test();
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n | column2
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---+---------
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1 | (1,2)
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1 | (3,4)
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(2 rows)
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ALTER TABLE changing DROP COLUMN j;
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SELECT * FROM changing_test();
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ERROR: length of returned sequence did not match number of columns in row
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CONTEXT: while creating return value
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PL/Python function "changing_test"
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SELECT * FROM changing_test();
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ERROR: length of returned sequence did not match number of columns in row
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CONTEXT: while creating return value
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PL/Python function "changing_test"
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ALTER TABLE changing ADD COLUMN j integer;
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SELECT * FROM changing_test();
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n | column2
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---+---------
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1 | (1,2)
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1 | (3,4)
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(2 rows)
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-- tables of composite types (not yet implemented)
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CREATE FUNCTION composite_types_table(OUT tab table_record[], OUT typ type_record[] ) RETURNS SETOF record AS $$
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yield {'tab': [['first', 1], ['second', 2]],
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'typ': [{'first': 'third', 'second': 3},
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{'first': 'fourth', 'second': 4}]}
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yield {'tab': [['first', 1], ['second', 2]],
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'typ': [{'first': 'third', 'second': 3},
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{'first': 'fourth', 'second': 4}]}
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yield {'tab': [['first', 1], ['second', 2]],
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'typ': [{'first': 'third', 'second': 3},
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{'first': 'fourth', 'second': 4}]}
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$$ LANGUAGE plpythonu;
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SELECT * FROM composite_types_table();
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ERROR: PL/Python functions cannot return type table_record[]
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DETAIL: PL/Python does not support conversion to arrays of row types.
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CONTEXT: PL/Python function "composite_types_table"
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-- check what happens if the output record descriptor changes
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CREATE FUNCTION return_record(t text) RETURNS record AS $$
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return {'t': t, 'val': 10}
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$$ LANGUAGE plpythonu;
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SELECT * FROM return_record('abc') AS r(t text, val integer);
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t | val
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-----+-----
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abc | 10
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(1 row)
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SELECT * FROM return_record('abc') AS r(t text, val bigint);
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t | val
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-----+-----
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abc | 10
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(1 row)
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SELECT * FROM return_record('abc') AS r(t text, val integer);
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t | val
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-----+-----
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abc | 10
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(1 row)
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SELECT * FROM return_record('abc') AS r(t varchar(30), val integer);
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t | val
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-----+-----
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abc | 10
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(1 row)
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SELECT * FROM return_record('abc') AS r(t varchar(100), val integer);
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t | val
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-----+-----
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abc | 10
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(1 row)
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SELECT * FROM return_record('999') AS r(val text, t integer);
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val | t
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-----+-----
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10 | 999
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(1 row)
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CREATE FUNCTION return_record_2(t text) RETURNS record AS $$
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return {'v1':1,'v2':2,t:3}
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$$ LANGUAGE plpythonu;
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SELECT * FROM return_record_2('v3') AS (v3 int, v2 int, v1 int);
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v3 | v2 | v1
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----+----+----
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3 | 2 | 1
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(1 row)
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SELECT * FROM return_record_2('v3') AS (v2 int, v3 int, v1 int);
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v2 | v3 | v1
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----+----+----
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2 | 3 | 1
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(1 row)
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SELECT * FROM return_record_2('v4') AS (v1 int, v4 int, v2 int);
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v1 | v4 | v2
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----+----+----
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1 | 3 | 2
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(1 row)
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SELECT * FROM return_record_2('v4') AS (v1 int, v4 int, v2 int);
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v1 | v4 | v2
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----+----+----
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1 | 3 | 2
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(1 row)
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-- error
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SELECT * FROM return_record_2('v4') AS (v1 int, v3 int, v2 int);
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ERROR: key "v3" not found in mapping
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HINT: To return null in a column, add the value None to the mapping with the key named after the column.
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CONTEXT: while creating return value
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PL/Python function "return_record_2"
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-- works
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SELECT * FROM return_record_2('v3') AS (v1 int, v3 int, v2 int);
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v1 | v3 | v2
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----+----+----
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1 | 3 | 2
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(1 row)
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SELECT * FROM return_record_2('v3') AS (v1 int, v2 int, v3 int);
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v1 | v2 | v3
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----+----+----
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1 | 2 | 3
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(1 row)
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