Re: Deleting duplicate rows using ctid ?

Am 06.02.24 um 00:32 schrieb David G. Johnston:
> On Mon, Feb 5, 2024 at 4:09 PM David Gauthier <dfgpostgres@gmail.com> 
> wrote:
>
>
>     I want the result to be just 2 recs, one for each dog.
>
>
> My present goto link for this question:
>
> https://harshitjain.home.blog/2019/06/17/postgresql-how-to-delete-duplicate-rows-in-postgresql/
>
> David J.
>

postgres=# select * from dogs;
  dog
------
  dog1
  dog1
  dog2
  dog2
  dog2
  dog3
(6 rows)

postgres=# select ctid, dog, row_number() over (partition by dog) from 
dogs ;
  ctid  | dog  | row_number
-------+------+------------
  (0,1) | dog1 |          1
  (0,2) | dog1 |          2
  (0,3) | dog2 |          1
  (0,4) | dog2 |          2
  (0,5) | dog2 |          3
  (0,6) | dog3 |          1
(6 rows)

postgres=# with ct as (select ctid, dog, row_number() over (partition by 
dog) from dogs) delete from dogs where ctid in (select ctid from ct 
where row_number != 1) ;
DELETE 3
postgres=# select * from dogs;
  dog
------
  dog1
  dog2
  dog3
(3 rows)

postgres=#


Regards, Andreas


-- 
Andreas Kretschmer
CYBERTEC PostgreSQL Services and Support