Re: Switching identity column to serial

On 04.02.23 21:55, Erik Wienhold wrote:
>>   Why doesn't this work?
>>   BEGIN;
>>   DROP SEQUENCE t_id;

[This won't work, you need to use ALTER TABLE / DROP IDENTITY.]

>>   CREATE SEQUENCE new_t_id_seq AS INTEGER OWNED BY t.id;
>>   ALTER SEQUENCE new_t_id_seq OWNER TO new_owner;
>>   SELECT setval('new_t_id', (SELECT MAX(id) FROM t));
>>   SELECT nextval('new_t_id');
>>   COMMIT;
> This should work but I want to preserve the existing sequence instead of
> re-creating it with the same properties.  That's why I was looking for a
> shortcut (also code golfing and sheer curiosity).

This is possible in principle, by implementing the inverse of the 
"Upgrading" recipe from 
<https://www.2ndquadrant.com/en/blog/postgresql-10-identity-columns/>. 
But if you don't want to figure that out, I think dropping and 
recreating the sequences as suggested here seems the best solution.