Re: Adding identity column to a non-empty table

On 10/15/2017 6:42 PM, Melvin Davidson wrote:
> On Sun, Oct 15, 2017 at 9:09 PM, Igal @ Lucee.org <igal(at)lucee(dot)org
> <mailto:igal(at)lucee(dot)org>> wrote:
>
> Melvin,
>
> On 10/15/2017 5:56 PM, Melvin Davidson wrote:
>>
>> On 10/15/2017 4:01 PM, Igal @ Lucee.org wrote:
>>
>>
>> Hello,
>>
>> I'm trying to add an identity column to a table that has
>> records (previously had a bigserial column which I removed):
>>
>>
>> There is probably a better solution, but the one I came up
>> with is to add the column as BIGSERIAL and DROP the SEQUENCE
>> CASCADE, SELECT the max(rid) + 1, and then convert the column
>> to IDENTITY:
>>
>>
>> The correct way to make r_id the primary key would be:
>>
>> ALTER TABLE  event_log
>>   ADD COLUMN r_id SERIAL;
>>
>> ALTER TABLE  event_log
>>   ALTER COLUMN r_id TYPE BIGINT,
>>   ADD CONSTRAINT dummy_pk PRIMARY KEY (r_id);
>>
>> That automatically generates the column as
>>
>> r_id bigint NOT NULL DEFAULT nextval('dummy_r_id_seq'::regclass),
>>   CONSTRAINT dummy_pk PRIMARY KEY (r_id)
>>
>> and creates the appropriate sequence for you.
>>
>
> Does that use the new IDENTITY construct that was added in
> Postgres 10?  I do not really care for the PRIMARY KEY
> constraint.  I just want the sequence with the benefits of the new
> IDENTITY "type".
>
>
> > Does that use the new IDENTITY construct that was added in Postgres 10?
>
> I cannot say, as I do not yet have PostgreSQL 10 installed because it
> was very recently released.
> However, the method I supplied works for all prior versions of PostgreSQL.

Understood.  But I already had a an auto-increment column by way of
BIGSERIAL.

I want specifically to use the new IDENTITY feature of Postgres 10.

Best,

Igal Sapir
Lucee Core Developer
Lucee.org <http://lucee.org/>