Remove orphaned label links and add a foreign key constraint
On GitLab.com, there are over 2 million orphaned label links out of
a total of 13 million. These orphaned label links can cause
quiet failures, such as unexpected nil values in ExportCsvWorker
.
It looks like about 1.4 million of these label links point to issues that no longer exist:
gitlabhq_production=# select count(*) from label_links where target_type = 'Issue' and not exists (SELECT 1 FROM issues where target_id = issues.id);
count
---------
1443644
(1 row)
Closes gitlab-org/gitlab-ee#7482
Edited by Stan Hu