Re: Does RAISE EXCEPTION rollback previous commands in a stored function?

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От Alexander Farber
Тема Re: Does RAISE EXCEPTION rollback previous commands in a stored function?
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Msg-id CAADeyWhtXG0uznEhyE68CPjGS5gQhnDmJ8f05ULCxkPmDfwnGg@mail.gmail.com
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Ответ на Re: Does RAISE EXCEPTION rollback previous commands in a stored function?  (Albe Laurenz <laurenz.albe@wien.gv.at>)
Ответы Re: Does RAISE EXCEPTION rollback previous commands in a stored function?  (Albe Laurenz <laurenz.albe@wien.gv.at>)
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Thank you, this is very helpful, just 1 little question:

Why do you write just EXCEPTION?

Shouldn't it be RAISE EXCEPTION?

Regards
Alex


On Wed, Mar 2, 2016 at 11:18 AM, Albe Laurenz <laurenz.albe@wien.gv.at> wrote:
Alexander Farber wrote:
> how to set such a savepoint inside of a stored function?
>
> Can I call "START TRANSACTION", and then at some point later in the same stored function call RAISE
> EXCEPTION?

I realize that what I wrote must be confusing.

You cannot use START TRANSACTION, BEGIN, SAVEPOINT, COMMIT or ROLLBACK
inside a function.  A function always runs within one transaction.

Savepoints or subtransactions are written with a BEGIN ... EXCEPTION
block in PL/pgSQL, so you could write:

DECLARE FUNCTION .... AS
$$BEGIN
   /* UPDATE 1 */
   UPDATE ...;
   BEGIN  /* sets a savepoint */
      /* UPDATE 2, can cause an error */
      UPDATE ...;
   EXCEPTION
      /* rollback to savepoint, ignore error */
      WHEN OTHERS THEN NULL;
   END;
END;$$;

Even if UPDATE 2 throws an error, UPDATE 1 will be committed.

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