Re: transactions in functions, possible bug or what I'm doing

On Fri, Nov 19, 2004 at 12:59:07PM +0000, Richard Huxton wrote:

> You can have what are called "savepoints" in version 8.0 though, which
> lets you trap errors and rollback to a named (saved) point in your function.

Savepoints in functions don't work as of 8.0.0beta4, unless I'm
doing something wrong:

CREATE TABLE foo (id SERIAL PRIMARY KEY, name TEXT NOT NULL);

CREATE FUNCTION fooins(TEXT) RETURNS BOOLEAN AS $$
BEGIN
SAVEPOINT x;
INSERT INTO foo (name) VALUES ($1);
ROLLBACK TO x;
RETURN TRUE;
END;
$$ LANGUAGE plpgsql;

BEGIN;
SELECT fooins('John');
ERROR: SPI_execute_plan failed executing query "SAVEPOINT x": SPI_ERROR_TRANSACTION
CONTEXT: PL/pgSQL function "fooins" line 2 at SQL statement

Error trapping does work, however:

CREATE FUNCTION fooins(TEXT) RETURNS BOOLEAN AS $$
BEGIN
INSERT INTO foo (name) VALUES ($1 || '-1');

BEGIN
INSERT INTO foo (id, name) VALUES (currval('foo_id_seq'), $1 || '-2');
EXCEPTION
WHEN unique_violation THEN
NULL;
END;

INSERT INTO foo (name) VALUES ($1 || '-3');

RETURN TRUE;
END;
$$ LANGUAGE plpgsql;

SELECT fooins('John');
fooins
--------
t
(1 row)

SELECT * FROM foo;
id | name
----+--------
1 | John-1
2 | John-3
(2 rows)

--
Michael Fuhr
http://www.fuhr.org/~mfuhr/