CREATE TABLE test1 (a int, b text);
CREATE PROCEDURE transaction_test1()
LANGUAGE plpythonu
AS $$
for i in range(0, 10):
    plpy.execute("INSERT INTO test1 (a) VALUES (%d)" % i)
    if i % 2 == 0:
        plpy.commit()
    else:
        plpy.rollback()
$$;
CALL transaction_test1();
SELECT * FROM test1;
 a | b 
---+---
 0 | 
 2 | 
 4 | 
 6 | 
 8 | 
(5 rows)

TRUNCATE test1;
DO
LANGUAGE plpythonu
$$
for i in range(0, 10):
    plpy.execute("INSERT INTO test1 (a) VALUES (%d)" % i)
    if i % 2 == 0:
        plpy.commit()
    else:
        plpy.rollback()
$$;
SELECT * FROM test1;
 a | b 
---+---
 0 | 
 2 | 
 4 | 
 6 | 
 8 | 
(5 rows)

TRUNCATE test1;
-- not allowed in a function
CREATE FUNCTION transaction_test2() RETURNS int
LANGUAGE plpythonu
AS $$
for i in range(0, 10):
    plpy.execute("INSERT INTO test1 (a) VALUES (%d)" % i)
    if i % 2 == 0:
        plpy.commit()
    else:
        plpy.rollback()
return 1
$$;
SELECT transaction_test2();
ERROR:  invalid transaction termination
CONTEXT:  PL/Python function "transaction_test2"
SELECT * FROM test1;
 a | b 
---+---
(0 rows)

-- also not allowed if procedure is called from a function
CREATE FUNCTION transaction_test3() RETURNS int
LANGUAGE plpythonu
AS $$
plpy.execute("CALL transaction_test1()")
return 1
$$;
SELECT transaction_test3();
ERROR:  spiexceptions.InvalidTransactionTermination: invalid transaction termination
CONTEXT:  Traceback (most recent call last):
  PL/Python function "transaction_test3", line 2, in <module>
    plpy.execute("CALL transaction_test1()")
PL/Python function "transaction_test3"
SELECT * FROM test1;
 a | b 
---+---
(0 rows)

-- DO block inside function
CREATE FUNCTION transaction_test4() RETURNS int
LANGUAGE plpythonu
AS $$
plpy.execute("DO LANGUAGE plpythonu $x$ plpy.commit() $x$")
return 1
$$;
SELECT transaction_test4();
ERROR:  spiexceptions.InvalidTransactionTermination: invalid transaction termination
CONTEXT:  Traceback (most recent call last):
  PL/Python function "transaction_test4", line 2, in <module>
    plpy.execute("DO LANGUAGE plpythonu $x$ plpy.commit() $x$")
PL/Python function "transaction_test4"
-- commit inside subtransaction (prohibited)
DO LANGUAGE plpythonu $$
s = plpy.subtransaction()
s.enter()
plpy.commit()
$$;
WARNING:  forcibly aborting a subtransaction that has not been exited
ERROR:  cannot commit while a subtransaction is active
CONTEXT:  PL/Python anonymous code block
-- commit inside cursor loop
CREATE TABLE test2 (x int);
INSERT INTO test2 VALUES (0), (1), (2), (3), (4);
TRUNCATE test1;
DO LANGUAGE plpythonu $$
for row in plpy.cursor("SELECT * FROM test2 ORDER BY x"):
    plpy.execute("INSERT INTO test1 (a) VALUES (%s)" % row['x'])
    plpy.commit()
$$;
ERROR:  cannot commit transaction while a cursor is open
CONTEXT:  PL/Python anonymous code block
SELECT * FROM test1;
 a | b 
---+---
(0 rows)

-- rollback inside cursor loop
TRUNCATE test1;
DO LANGUAGE plpythonu $$
for row in plpy.cursor("SELECT * FROM test2 ORDER BY x"):
    plpy.execute("INSERT INTO test1 (a) VALUES (%s)" % row['x'])
    plpy.rollback()
$$;
ERROR:  cannot abort transaction while a cursor is open
CONTEXT:  PL/Python anonymous code block
SELECT * FROM test1;
 a | b 
---+---
(0 rows)

DROP TABLE test1;
DROP TABLE test2;