The patch to disallow a NULL specification in combination with
GENERATED ... AS IDENTITY applied to both ALWAYS and BY DEFAULT
variants of that clause, not only the former.
Noted by Shay Rojansky.
Discussion: https://postgr.es/m/CADT4RqAwD3A=RvGiQU9AiTK-6VeuXcycwPHmJPv_OBCJFYOEww@mail.gmail.com
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<para>
- <literal>GENERATED ALWAYS AS IDENTITY</literal> implies <literal>NOT
+ <literal>GENERATED ... AS IDENTITY</literal> implies <literal>NOT
NULL</literal>, so don't allow it to be combined with an
explicit <literal>NULL</literal> specification.
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