Error importing backup: "could not create unique index"

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Ok, I’ve fixed it. I did the following

Enter container

./launcher enter app

Connect to database

su postgres -c 'psql discourse'

Try to find duplicates

discourse=# select * from incoming_referers where path LIKE '%/search/' ORDER BY incoming_domain_id;`

  id  |    path    | incoming_domain_id
------+------------+--------------------
 3339 | /search/   |                 33
 6257 | /search/   |                 91
 1567 | /search/   |                298
 1777 | /search/   |                341
 3010 | /search/   |                418
 6247 | /search/   |                418
 4293 | /search/   |                644
 2899 | /search/   |                653
 3447 | /search/   |                793
 3696 | /search/   |                852
 4395 | /a/search/ |               1050
 6968 | /search/   |               1305
 5634 | /search/   |               1387
 5834 | /search/   |               1437
 6519 | /search/   |               1637
 7127 | /search/   |               1787
 7280 | /search/   |               1827
(17 rows)

Delete duplicate

DELETE FROM incoming_referers WHERE path LIKE '%/search/' AND id IN (6247);

Then rebuild

discourse=# REINDEX SCHEMA CONCURRENTLY public;
WARNING:  cannot reindex invalid index "public.incoming_referers_pkey_ccnew" concurrently, skipping
WARNING:  cannot reindex invalid index "public.index_incoming_referers_on_path_and_incoming_domain_id_ccnew" concurrently, skipping
WARNING:  cannot reindex invalid index "pg_toast.pg_toast_20732_index_ccnew" concurrently, skipping
REINDEX

Then I took another backup, copied it to the new server, and it imported successfully :smiley:

It would be nice if the backup process could spot duplicates to avoid any issues, I was luckily that I had access to the original server which was still running. If I was restoring a cold backup, this would probably have been more of an issue>

Thanks a lot for your help.