Re: Merging records in a table with 2-columns primary key
| От | Alexander Farber |
|---|---|
| Тема | Re: Merging records in a table with 2-columns primary key |
| Дата | |
| Msg-id | CAADeyWj7K6V=E+rLNEksEtWjPVVc_2Rxkw3Mz=xmvY2vp8vC8Q@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Merging records in a table with 2-columns primary key (Andy Colson <andy@squeakycode.net>) |
| Список | pgsql-general |
Hello Andy and others -
On Sun, Apr 2, 2017 at 5:13 PM, Andy Colson <andy@squeakycode.net> wrote:
On 04/02/2017 09:26 AM, Alexander Farber wrote:http://stackoverflow.com/questions/43168406/merging-records- in-a-table-with-2-columns- primary-key
after some thinking, when I call
SELECT out_uid FROM merge_users(ARRAY[1,2,3,4]);
then "reviews" table should be empty (get rid of all self-reviews)
and "users" should contain just 1 record (1, 'User 1').
And if instead I call
SELECT out_uid FROM merge_users(ARRAY[1,2]);
then "reviews" should be (records with User 2 removed because overlapped with User 1):
uid | author | review
-----+--------+------------------------
1 | 3 | User 3 says: 1 is nice
1 | 4 | User 4 says: 1 is nice
3 | 1 | User 1 says: 3 is nice
3 | 4 | User 4 says: 3 is ugly
4 | 1 | User 1 says: 4 is ugly
4 | 3 | User 3 says: 4 is ugly
and "users":
uid | name
-----+--------
1 | User 1
3 | User 3
4 | User 4
So my 2 questions are -
1) Why the error when calling merge_users(ARRAY[1,2]) and then merge_users(ARRAY[1,2,3,4])?
2) Is there a way to use an UPDATE reviews instead of the inefficient (because copying) INSERT ... SELECT ... ON CONFLICT DO NOTHING?
Thank you
Alex
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