PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
> -- insert more than one row with "id" set to DEFAULT;
> -- result: unexpected and undocumented failure with the following error:
> -- ERROR: cannot insert into column "id"
> -- DETAIL: Column "id" is an identity column defined as GENERATED
> ALWAYS.
> -- HINT: Use OVERRIDING SYSTEM VALUE to override.
> INSERT INTO test (id, name) VALUES (DEFAULT, 'Adam'), (DEFAULT, 'Eve');
Yeah, this is a known deficiency. It's fixed for v14, but the
fix was deemed too invasive to risk back-patching [1].
regards, tom lane
[1] https://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=17958972f