Re: FOR PORTION OF should reject GENERATED columns

On 29.06.26 08:29, Paul A Jungwirth wrote:
> On Sat, Jun 27, 2026 at 12:05 AM Peter Eisentraut <peter(at)eisentraut(dot)org> wrote:
>>
>>> The test about BEGIN ATOMIC functions now shows that the analysis-time
>>> check prevents you from defining the function.
>>
>> Hmm, I think doing it in the parser won't actually work if you are
>> writing through a view. For example, with the v4 patch, the following
>> does not error:
>>
>> CREATE TABLE t (a int, b int4range GENERATED ALWAYS AS (int4range(a, a +
>> 1)) STORED);
>> CREATE VIEW v AS SELECT * FROM t;
>> DELETE FROM v FOR PORTION OF b FROM 1 TO 2;
>>
>> So we need to push it later after all.
>>
>> But maybe it would fit in the planner, near where the volatility check
>> is being moved to?
>
> That's a good catch. Here is a version that checks in the planner,
> with your example added to the test cases. This is a little nicer than
> the executor, since rangeVar hasn't been converted to an expression
> yet (for VIRTUAL columns).

It seems like this still doesn't fully work in some situations:

-- as before
CREATE TABLE t (a int, b int4range GENERATED ALWAYS AS (int4range(a, a +
1)) STORED);
CREATE VIEW v AS SELECT * FROM t;

-- now with an INSTEAD OF trigger
CREATE FUNCTION tfunc() RETURNS trigger LANGUAGE plpgsql AS $$
BEGIN RETURN OLD; END;
$$;

CREATE TRIGGER tg1
INSTEAD OF DELETE ON v
FOR EACH ROW EXECUTE FUNCTION tfunc();

-- This should fail but doesn't.
DELETE FROM v FOR PORTION OF b FROM 1 TO 2;