Re: [GENERAL] Adding identity column to a non-empty table

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):
>
>   ALTER TABLE event_log
> ADD COLUMN r_id BIGINT GENERATED BY DEFAULT AS IDENTITY;
>
> But I'm getting an error `column r_id contains null values`.
>
> How can I add the column and populate it for the existing rows?
>

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:
  ALTER TABLE transient.event_log ADD COLUMN r_id BIGSERIAL;
  -- find the sequence name and then  DROP sequence <sequence-name> CASCADE;
  -- find min value by executing select max(r_id) + 1  ALTER table transient.event_log      ALTER COLUMN r_id         
ADDGENERATED BY DEFAULT AS IDENTITY (MINVALUE <min-value>);
 

If anyone has a better suggestion then please let me know.

Thanks,


Igal



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