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.
>
>
>> 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?
>
Yes. Plain SERIALs can be updated with given values
whereas IDENTITY columns cannot. And there is the
difference between GENERATED and GENERATED IDENTITY:
GENERATED columns can updated with DEFAULT
values, IDENTITY columns cannot. I strictly have to
distinguish IDENTITY from both GENERATED and
plain SERIALs.
> regards, tom lane
>
--
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Zoltán Böszörményi
Cybertec Geschwinde & Schönig GmbH
http://www.postgresql.at/