Re: IDENTITY/GENERATED v36 Re: Final version of IDENTITY/GENERATED patch

Zoltan Boszormenyi írta:
> Tom Lane írta:
>> Zoltan Boszormenyi <zb@cybertec.at> writes:
>>
>>> So, I should allow DROP DEFAULT, implement
>>> SET DEFAULT GENERATED ALWAYS AS
>>> and modify the catalog so the GENERATED property
>>> is part of pg_attrdef.
>>>
>>
>> Sounds good.
>>
>
> Finally here it is.
>
>>> What about IDENTITY?
>>> Should it also be part of pg_attrdef? There are two ways
>>> to implement it: have or don't have a notion of it.
>>> The latter would treat GENERATED BY DEFAULT AS IDENTITY
>>> the same as SERIAL.
>>>
>>
>> Is there any good reason to distinguish the two?
>>
>
> Actually, I needed to have a flag for IDENTITY
> but not for the reason above. I need it to distinguish
> between GENERATED ALWAYS AS IDENTITY
> and GENERATED ALWAYS AS ( expr ).
>
> Changes:
> - Rewritten the GENERATED/IDENTITY flags to be part of the default
> pg_attrdef
>   This made the patch MUCH smaller.
> - SERIALs are now the same as INTEGER GENERATED BY DEFAULT AS IDENTITY
> - Allow DROP DEFAULT on GENERATED/IDENTITY columns
> - Implemented SET GENERATED ALWAYS AS
> - Modified syntax of SET GENERATED {ALWAYS | BY DEFAULT} AS IDENTITY
>    so it reads as SET IDENTITY GENERATED {ALWAYS | BY DEFAULT}
>    so compiling gram.y/gram.c doesn't give me errors.
>    This DDL statement isn't part of SQL:2003 so it might be accepted
>    as a PostgreSQL extension.
> - Modified behaviour of SET IDENTITY to also restore the DEFAULT
>    expression. Someone might have done did a DROP DEFAULT before
>    but kept the OWNED sequence.
> - Fixed behaviour of GENERATED columns regarding
>    INSERT ... OVERRIDING SYSTEM VALUE and
>    only those GENERATED columns get UPDATEd that
>    are either explicitly modified with SET column = DEFAULT
>    or one of their referenced columns are modified.
> - Testcase and documentation is modified to reflect the above.

- Also allowed UPDATE on IDENTITY columns.

>
> Please, review.
>
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Zoltán Böszörményi
Cybertec Geschwinde & Schönig GmbH
http://www.postgresql.at/