1 files changed, 28 insertions, 0 deletions
diff --git a/db/migrate/20190527135836_fill_array_column_for_labels.rb b/db/migrate/20190527135836_fill_array_column_for_labels.rb
new file mode 100644
index 00000000000..d40bd1c4e85
--- /dev/null
+++ b/db/migrate/20190527135836_fill_array_column_for_labels.rb
@@ -0,0 +1,28 @@
+class FillArrayColumnForLabels < ActiveRecord::Migration[5.1]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    update!('issues')
+    update!('merge_requests')
+  end
+
+  private
+
+  def update!(table)
+    execute <<-SQL
+      UPDATE #{table}
+      SET label_titles = subquery.label_titles
+      FROM
+        (
+          SELECT #{table}.id AS id, array_agg(labels.title) AS label_titles
+          FROM #{table}
+          LEFT JOIN label_links ON target_id = #{table}.id AND label_links.target_type = 'Issue'
+          LEFT JOIN labels ON label_id = labels.id
+          GROUP BY #{table}.id
+        ) AS subquery
+      WHERE #{table}.id = subquery.id;
+    SQL
+  end
+end