1 files changed, 32 insertions, 0 deletions
diff --git a/db/migrate/20161017125927_add_unique_index_to_labels.rb b/db/migrate/20161017125927_add_unique_index_to_labels.rb
new file mode 100644
index 00000000000..16ae38612de
--- /dev/null
+++ b/db/migrate/20161017125927_add_unique_index_to_labels.rb
@@ -0,0 +1,32 @@
+class AddUniqueIndexToLabels < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = true
+  DOWNTIME_REASON = 'This migration removes duplicated labels.'
+
+  disable_ddl_transaction!
+
+  def up
+    select_all('SELECT title, COUNT(id) as cnt FROM labels GROUP BY project_id, title HAVING COUNT(id) > 1').each do |label|
+      label_title = quote_string(label['title'])
+      duplicated_ids = select_all("SELECT id FROM labels WHERE title = '#{label_title}' ORDER BY id ASC").map{ |label| label['id'] }
+      label_id = duplicated_ids.first
+      duplicated_ids.delete(label_id)
+
+      execute("UPDATE label_links SET label_id = #{label_id} WHERE label_id IN(#{duplicated_ids.join(",")})")
+      execute("DELETE FROM labels WHERE id IN(#{duplicated_ids.join(",")})")
+    end
+
+    remove_index :labels, column: :project_id if index_exists?(:labels, :project_id)
+    remove_index :labels, column: :title if index_exists?(:labels, :title)
+
+    add_concurrent_index :labels, [:group_id, :project_id, :title], unique: true
+  end
+
+  def down
+    remove_index :labels, column: [:group_id, :project_id, :title] if index_exists?(:labels, [:group_id, :project_id, :title], unique: true)
+
+    add_concurrent_index :labels, :project_id
+    add_concurrent_index :labels, :title
+  end
+end