Re: Identity column behavior discrepancies when inserting one or many rows

Here is a very simple script to reproduce what we encountered :

CREATE TABLE test (
   id int GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
   sometext text NOT NULL
);

-- that one works : INSERT 0 1
-- I think it should not and throw a 428C9
INSERT INTO test (id, sometext)

VALUES (DEFAULT, 'test');

-- this one does not : SQL state : 428C9
INSERT INTO test (id, sometext)

VALUES (DEFAULT, 'test2'),
(DEFAULT, 'test3');

 

Though GENERATED ALWAYS implies the absence of the identity column in the column names list of any INSERT statement, listing it there is OK, without the OVERRIDING SYSTEM VALUE flag, as long as only one row is inserted (and DEFAULT is used as value, of course). But starting at 2 rows (and I can only guess it never stops), the proper error is thrown, advising to use the aforementioned flag.

Is there any reason I missed such behavior would be expected ?