diff options
Diffstat (limited to 'db/post_migrate/20180906051323_remove_orphaned_label_links.rb')
-rw-r--r-- | db/post_migrate/20180906051323_remove_orphaned_label_links.rb | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/db/post_migrate/20180906051323_remove_orphaned_label_links.rb b/db/post_migrate/20180906051323_remove_orphaned_label_links.rb new file mode 100644 index 00000000000..b56b74f483e --- /dev/null +++ b/db/post_migrate/20180906051323_remove_orphaned_label_links.rb @@ -0,0 +1,43 @@ +# frozen_string_literal: true + +class RemoveOrphanedLabelLinks < ActiveRecord::Migration + include Gitlab::Database::MigrationHelpers + + DOWNTIME = false + + disable_ddl_transaction! + + class LabelLinks < ActiveRecord::Base + self.table_name = 'label_links' + include EachBatch + + def self.orphaned + where('NOT EXISTS ( SELECT 1 FROM labels WHERE labels.id = label_links.label_id )') + end + end + + def up + # Some of these queries can take up to 10 seconds to run on GitLab.com, + # which is pretty close to our 15 second statement timeout. To ensure a + # smooth deployment procedure we disable the statement timeouts for this + # migration, just in case. + disable_statement_timeout do + # On GitLab.com there are over 2,000,000 orphaned label links. On + # staging, removing 100,000 rows generated a max replication lag of 6.7 + # MB. In total, removing all these rows will only generate about 136 MB + # of data, so it should be safe to do this. + LabelLinks.orphaned.each_batch(of: 100_000) do |batch| + batch.delete_all + end + end + + add_concurrent_foreign_key(:label_links, :labels, column: :label_id, on_delete: :cascade) + end + + def down + # There is no way to restore orphaned label links. + if foreign_key_exists?(:label_links, column: :label_id) + remove_foreign_key(:label_links, column: :label_id) + end + end +end |