Re: ROLLBACK automatically

> And what if I didn't want the commit to fail? What if I half expected
> the insert
> to fail and then want to do an update instead? That's a pretty common
> pattern - try
> to insert, if fail - do an update instead.
>
> Is this behaviour some kind of standard? Can it be changed?

Not in this life :)

PostgreSQL does not support nested transactions. If transaction fails, the
transaction fails.

You may write a trigger instead of (or combined with) UNIQUE CHECK, like
this:

CREATE FUNCTION fn_foo_insupd() RETURNS OPAQUE AS '
DECLARE
    chk INT4;
BEGIN
    SELECT id INTO chk FROM foo WHERE id = NEW.id;
    IF FOUND THEN
        PERFORM some_action(NEW.id);
        RETURN NULL;
    END IF;
    RETURN NEW;
END;
' LANGUAGE 'plpgsql';

CREATE TRIGGER trg_foo_insupd BEFORE INSERT OR UPDATE ON foo FOR EACH ROW
EXECUTE PROCEDURE fn_foo_ins();

Note that if you insert a row into a keyed table that has a trigger, you
cannot delete this row or update the key in the same transaction.

Alex Bolenok.